How to Convert Units of Measure!

Alright, let’s talk about how to convert
units of measure. Maybe the concept that is used the most
in any science class because almost every single problem is going to require
you to convert units in chemistry physics biology kind of whatever
converting units is a big one that never leaves once you learn it and you’ll see
lots of different ways on how to convert units and because it’s kind of just
using fraction math there are lots of different ways to show it lots of ways
to draw brackets or different things to help people remember it and the way that
I’m going to go over today is kind of the longest way possible this is the
anti shortcut way which sounds annoying but I think that this is the way that
fundamentally explains it and if you are struggling and if every time you have to
convert units you just find yourself flustered and lost you don’t know which
number to pick or where to put it this is the way that really explains that so
this is not the way that’s going to get done in like a minute but this is the
way that’s going to help you understand and even if you don’t know what’s
happening as long as you carefully follow all of these steps you’re going
to get the right answer so if you’re just starting out or struggling this is
the way for you and so let’s start we’ll be doing our practice problem how to
convert 16 centimeters into meters and so step one is to identify your
conversion ratio and so in every conversion problem we’re going from one
unit to another and there’s always some ratio that’s going to connect those two
and this is kind of how to find this is kind of more of an introduction on the
metric system or something else so we’re just going to start with
assuming that you know how to find your conversion ratio for this problem and so
that means that we have to know the relationship between centimeters and
meters and so that relationship is that a hundred centimeters equals one meter
and so this is our conversion ratio that’s step one we’re done we know that
this is how centimeters and meters relate to each other so step two write
your conversion ratio as its two possible fractions and what I mean
by that is that your equal sign is now going to become your fraction bar and so
for this are two possible options are 100 centimeters over one meter and then
our other option is one meter over 100 centimeters and so I made both of them
because I don’t know which one I’m going to need yet all I know is that I have my
conversion ratio and this equal sign is now going to turn into a fraction where
either one could be on top so that’s always what you’re going to do is just
make these two different fractions with both opposite options on top and so now
step three draw your given number as a fraction including units and this is
really important because every number is secretly a fraction whether or not it
shows it and so the number that we got in the problem is just written like this
16 centimeters and now we’re going to draw that as a fraction and so what that
means is that if there’s no fraction like seen immediately it means that this
is secretly a numerator and so if it’s secretly a numerator then when we draw
it out it’s going to be like this 16 and centimeters very important are both on
the numerator and our denominator is just one because remember that if our
denominator is one then really what we see on the numerator that just is our
total answer and so this step is really important and never drop the unit’s all
students want to drop units it’s just in their blood don’t do it especially in
these problems we’re converting units make sure that you know that you’re
centimeters is on the numerator it’s very important okay great so now that we
have all of our prep work done we’re ready to do the actual problem and so
step four pick the best conversion fraction multiply and solve okay so for
this first example I’m just going to set everything up so we have our 16
centimeters over one this is our actual number now
all written as a fraction and so step one or option one is that we just
multiply it with this guy this is the first conversion fraction that we made
so let’s just set that up and then we have another or situation because we
could multiply it with this guy so let’s set that guy up too so it’s our same
number or same number that’s getting converted 16 centimeters over 1 and now
we have this second fraction so one meter over 100 centimeters all right so
one of these is going to be correct and one of these is going to be wrong so now
let’s just do the math and solve so if we multiply across the top on the
numerator here we’re going to get 16 times 100 and so that’s going to be 1600
and then remember we have to multiply our numerator so this is not going to
cancel out we have two centimeters on top so that means that our answer for
this will be centimeters squared and then our ones are going to multiply
that’s just going to be one and then our meter didn’t cancel out or do anything
so that’s going to be still here so option number one we got 1600
centimeters squared over one meter now this is an ugly gross answer we don’t
want this so this was the wrong choice so now let’s see what the choice was
with the correct conversion fraction so over here we have and this is the most
important part our cancellation this centimeters is on top and this one’s on
bottom so we can cancel them out and so now we multiply it’s going to be 16
times 1 so just going to be 16 and our unit is going to be meters and then on
the bottom it’s just going to be 1 times 100 so that’s just going to be a hundred
and there is no unit on the bottom because centimeter got cancelled out so
now we have 16m over a hundred and just to simplify put it into a decimal or
calculator we get 0.16 and our unit is meter and so this is our correct answer
and let’s assume we’re taking a science class we have to do sig figs here so our
original problem had one two sig figs just one for each non zero and then our
final answer this is not a sig fig both of these are remember that leading zeros
are never sig figs so our final answer has two sig figs so that’s correct and
so in these problems our conversion ratios don’t really count as sig figs
you wouldn’t count any sig figs for this or this because it’s considered like a
perfect number so one hundred centimeters and equals one meter that’s
not a measurement we didn’t like go into lab and say okay we figured that out
that’s just kind of a perfect thing that all of science assumes so we don’t have
to use sig figs from those two numbers all right now let’s do a couple more
practice problems all right so starting with our first problem
convert point six eight five milligrams into grams so just going to do the same
four steps and do them really diligently and we won’t get misled into a wrong
answer so step one identify your conversion ratio so in this case we’re
comparing milligrams and grams and so the relationship is that a thousand
milligrams equals one gram all right and so now we’re going to write our two
possible conversion fractions so our equal sign just literally becomes a
fraction and so it doesn’t matter what you start with on top there’s only two
options since you only have two things so our two fraction options are a
thousand milligrams over one gram or one gram over a thousand milligrams all
right so one of these is going to be the conversion unit that we need alright so
step three draw your given number as a fraction including units and so I’d pick
this example because even decimals can secretly be fractions
so if you have a decimal just use it as normal and put point six eight five and
milligrams they’re all going to be on the numerator and then you can just
throw a 1 under it and that’s still completely fine and so just be really
careful make sure your units are still in the numerator and so now step 4
pick the best conversion fraction multiply and solve so we’re going to set
up our original problem number and now we have to pick what conversion fraction
is going to go right here which one is going to help us solve and so for that
we’re going to do a little bit of thinking ahead and our big goal here is
to cancel out milligrams the whole point of the problem is to get rid of
milligrams and put it into grams and so we can see if we put this guy in there
milligrams is going to be on the numerator and that means that you’re
going to end up with something milligrams squared and then our grams is
going to be on the denominator and that’s not right so what we don’t want
is to use that one and we do want to use this guy because we can see right here
this milligrams on the bottom is going to cancel out with the milligrams that
we have on top from our number so this is the one that’s going to help us out
so we can fill this in one gram over a thousand MiG’s all right and so now
let’s do some calculator math I don’t feel like solving this right now so we
plug that in and we get point zero zero zero six eight five and then our unit is
grams this cancels out and this is our number and so now let’s again assume
we’re doing it in a science class not a math class we’re going to then have to
do sig figs and so our original problem this doesn’t count the leading zero one
two three sig figs so we want our final answer to have three sig figs so none of
these leading zeros count one two three so this ended up in three
so this is correct and remember that in a conversion none of these are going to
count for sig figs we just ignore them the only one that was given to us only
one that’s a measurement is this first point 685 okay cool and now let’s do our
last example convert an eighth of a liter in to milliliters all right and so
step one identify your conversion ratio once again we’re just dealing with two
different units liter and milliliters so one liter equals a thousand milliliters
so our two conversion ratios and they’re two possible fractions are one liter
over a thousand mils or a thousand mils over one liter and so now we’re going to
draw our given number as a fraction including units and so once again I gave
you a different type of number to force you to think about where your units go
and what happens when you convert a number into a fraction and so this says
convert in eighth of a liter so if we just draw that out it’s going to be 1/8
and the way that you see unit’s written next to fractions is usually like this
they’re right in the middle so 1/8 of a liter and this is pretty typical but
it’s really important to know what that actually means because when we have to
assign that unit to a part of our fraction we have two options right we
could do this we could do one liter over 8 or we could do this one over 8 liters
and one is correct and one is incorrect and so the big thing to really know is
that unless stated otherwise your unit is on the numerator so this is the
correct one we were not told here that this was the denominator it just was in
kind of neutral it’s kind of hanging off to the side but it actually means this
not this so if we meant that it was 1 over 8 liters which is completely
possible that could be in a science problem or a math problem we would just
have to be told that it would have meant that in our original problem that would
have been shown okay so now we have our step three done
and so now we’re going to pick our best conversion fraction multiply and solve
so one liters over eight and I just use the parentheses because I think that
they kind of make it easy to see you don’t need to be using them and so we
have our two options and so now thinking ahead to which one is going to cancel
out so we want our leaders down here because that is the only way that
they’re going to cancel out right so our most important thing is to say which
conversion fraction allows us to get the leaders in the denominator because
that’s the way we’re going to get rid of it and make room for the milliliters and
so now if we go we look at our two different conversion fractions the only
one that has leaders in the denominator is this one which means this is the one
we have to plug in this is the one that’s going to allow the correct
cancelling and the right answer to appear all right so now let’s do our
multiplication and do some canceling out so if we cancel these guys out and we
know we’re going to end up in mill and so basically we have a thousand over
eight and that turns into 125 and so that’s our answer so just talk about sig
figs a little bit in this problem so we had it written up here as an eighth it
was just words not numbers and so the way that I run my classes is when you
see that it means that you don’t consider sig figs that you just consider
it to be an eighth is like a perfect number kind of like our conversion
ratios we wouldn’t consider one liter or a thousand mils to either them have sig
figs but I think every teacher kind of does it on their own so if you’re in
taking a test and you don’t remember what your teacher said and you see some
kind of word written out you can definitely ask them that’s fair game
there’s not one standard way that everyone should be doing that that’s all
I have for you today I hope you enjoyed this longer very detailed explanation of
how to convert units again I really think that if you store
with this topic this is the way that makes you think about every step that
doesn’t allow you to have a pitfall where you take a wrong turn this is
really the way that forces you to do it correctly even though it takes longer
but hey when you rather take longer and get the answer right then do a shortcut
you don’t understand and not know if you got it right this is the teacher nagging
side of me coming out I can’t control happens everybody starts teaching
chemistry I think anyway that’s all I have for you today I hope you enjoy this
video and have a good day

37 thoughts on “How to Convert Units of Measure!

  1. how bad hand writing and i never see so bad hand writing but it helpful and sorry for this and please don't mind that i have please and math are very improtant for our life . write my comment and i write some more comment and please don't mind . i think your are aesome

  2. This is a really complicated way and noone who uses the metric system daily use fractions to do conversions. You just move the decimal point. Example: convert 200 cm to meters, move the decimal point 2 places and you get 2 meters. That's the beauty and simplicity of the metric system. Just move the decimal point.

  3. Thank you so much for sharing your knowledge on conversions! This has helped me tremendously I have a much better grasp on the subject. Much appreciated!

  4. This method is unnecessarily complicated. I personally would start with the conversion ratio but from there on its all different. 100cm = 1m (divide both sides by 100 to find 1cm) 1cm = 1m/100 (multiply both sides by 16) 16cm = 1m x 16 /100 therefore 16cm = 0.16m. A lot simpler imo.

  5. Thanks for this video. I wasn't understanding this formula in my class, and I have to retake my test tomorrow because I initially failed it, but your explanation makes me feel confident that I can pass tomorrow.

  6. Thank you for this channel. It seems like my chem professor won't be one to discuss things in detail. Your videos will be a cornerstone of supplemental instruction for me. You are amazing !!

  7. Thank you so much! I was getting confused on how to set up the conversation equations! Studying for the state certification exams. I am certainly not going to be a math teacher!

  8. This is great. No point using shortcuts if you don't know what they're for.

  9. If you have an eighth and you put that in the calculator it gives you three sig figs, which is what you had in the answer.. can you do it that?

  10. Sorry I got lost halfway, too many choices.Too much room for error and if your a complete maths biff how would you know that you multiply?

  11. This is exactly how my professor is teaching us conversions and I was really confused. You explained it well and now I have a better understanding :'D tears of joy

  12. Thank you thank you thank you. I've seen so many conversions I just needed it explained fully and you have done that.

  13. I can not thank you enough for taking time to put this video out in the universe. I have my conversion test today. It's an accelerated program and material was only introduced to us on Friday. Its Monday and we test @ 830 am . Its 6 am and I finally see the light ,THANKS TO YOUR TEACHING TECHNIQUE. AN AWESOME TEACHER CAN MAKE ALL THE DIFFERENCE THAT WILL EITHER MAKE OR BREAK A STUDENT. OUR INSTRUCTOR IS BREAKING THOSE OF US WHO JUST NEED IT PRESENTSED FOR VISUAL LEARNERS. I THINK WITH YOUR HELP IM GOING TO MAKE IT. MAY YOU BE BLESSED WITH ALL THE BEAUTY YOU DESERVE…. ✌

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