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### Course: 4th grade > Unit 8

Lesson 5: Adding and subtracting mixed numbers- Adding mixed numbers with like denominators
- Subtracting mixed numbers with like denominators
- Add and subtract mixed numbers (no regrouping)
- Mixed number addition with regrouping
- Subtracting mixed numbers with regrouping
- Add and subtract mixed numbers (with regrouping)

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# Subtracting mixed numbers with regrouping

Sal practices subtracting mixed numbers with common (like) denominators. Items require regrouping (borrowing).

## Want to join the conversation?

- why doesn't khan academy have a video about subtracting mixed numbers from whole numbers? if it does, where is it?(12 votes)
- Subtracting mixed numbers from whole numbers is really basic. You first subtract the whole number parts and find the difference. You then reduce the difference by 1, keep that as the whole number part, "copy and paste" the denominator of the mixed number into the denominator of the difference, then subtract the value in the denominator of the mixed number by the value in the numerator (of the mixed number), then put that difference into the answer's numerator.

In other words, subtracting mixed numbers from whole numbers means you are subtracting mixed numbers by mixed numbers, except the fraction part of the mixed number of what is actually a "whole number" equals 0.(15 votes)

- But why did he change the 4 to a 3, is he subtracting?(10 votes)
- Another way to solve this problem is to simply convert our two mixed numbers into improper fractions, than we have a simpler subtraction (17/4-10/4)and then just convert what remains after this subtraction (7\4) back to a mixed number as our final result

( 1"whole" and 3\4 = 1 3\4).(3 votes) - I have watched the vid but I am still quiry/confused.(2 votes)
- can fractions be considered as even or odd?(1 vote)
- No. Only integers can be even or odd.(2 votes)

- i am confused. if i covert 1/4 to the one fourth will it still work?(1 vote)
- is the mixed numbers part of the Question?(1 vote)
- I am still very confused on the whole concept(1 vote)
- i really need to get go at this because i am all most going to 5th grade!(0 votes)
- here let me help. Think about 8 2/8 - 3 3/8 so, first, borrow 1 from 8 and add it to the 2/8 since one is a whole it is also like 8/8 so 8+2=10 so now you have 10/8 then resume normally 10/8 - 3/8 = 7/8 and 7-3=4 so the outcome would be 4 7/8(3 votes)

- why did he confert the 4 into a 3 ?(0 votes)

## Video transcript

- [Instructor] So let's
see how we could approach four and 1/4 minus two and 2/4. Pause this video and have a go at that before we work on this together. All right, so the first thing
that you might try to do is re-write this as four
and 1/4 minus two and 2/4. And the reason why it's
useful to write it this way is we could say look,
each of these mixed number have a whole number part and then they have a fractional part. And so I could try to
subtract the fractional part from the fractional part and then the whole number part
from the whole number part. And that will often work. But when we go to just
the fractional parts and we say hey, how do
I subtract 2/4 from 1/4, 2/4 is larger than 1/4. You immediately might find yourself in something of a conundrum. So what do you do? Well, what comes to the rescue
is a notion called regrouping and that's that we're not
just subtracting 2/4 from 1/4. We're subtracting two and
2/4 from four and 1/4. So what we could do is we
could take some of the value that's in this four and
regroup it into the fraction. What do I mean by that? Well instead of four, if I view four as three and 4/4, 4/4. And so 4/4 plus 1/4 is 5/4, 5/4. So I could re-write this as three and 5/4 minus two and 2/4. Once again, why is that useful? Because 5/4 is greater than 2/4. What is 5/4 minus 2/4? Well that's going to be 3/4. And then what is three minus two? Well that's going to be one. And we get one and 3/4. Another way we could of thought about it is this is the same
thing as four minus two plus 1/4, plus 1/4, minus 2/4, minus 2/4. And we have trouble
with the 1/4 minus 2/4. That's what we saw right over here. So what we do is we take some
of that value from the four. Instead of four we could
re-write that as three plus 4/4. That's the same thing as four. And of course you have minus
two plus 1/4 minus 2/4. And then if you add the 4/4 to the 1/4 that's going to give us 5/4. So you're going to have three minus two. That's that part and that part. And then you're going to have if you add the 4/4 and the 1/4, so plus 5/4 minus 2/4. And that exactly what we have here. Three and 5/4, three and 5/4 minus two, minus two, and minus 2/4. And so three minus two is one. 5/4 minus 2/4 is 3/4.