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Stesso

Equating Denominators and Borrowing

0:10
1:54
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Subtracting fractions aint gotta be hard!

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What happens here

To subtract fractions, their denominators must be the same. The presenter demonstrates converting 5/8 to an equivalent fraction with a denominator of 16 by multiplying both the numerator and denominator by 2, resulting in 10/16. He then highlights that directly subtracting 9/16 by 10/16 would result in a negative numerator (-1/16), which is not ideal for mixed fraction subtraction. To overcome this, he 'borrows' one whole number from the 11 (making it 10) and converts that whole number into an equivalent fraction of 16/16. This is then added to the original 9/16, yielding 25/16. The problem is then rewritten as 10 and 25/16 minus 5 and 10/16, preparing for straightforward subtraction.

Goal: Prepare fractions for subtraction by having common denominators and handling borrowing

Tools and materials

  • Whiteboard Marker — Writing on the whiteboard
  • Whiteboard US General — Writing down the math problems and explanations

What they say

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and 5/8, right? All right, let's turn this one to the 16. So, * 2. What you do on here, you got to do on here, right? So, 10 over 16, right? Boom, boom, boom, boom, boom. Okay? So, let's rewrite this. 5 and 10/16. So, now you got to take 9 - You can't do that. You can't do 9 - 10 cuz you get -1. That don't work, right? So, what we did in previous videos, we added these two. So, we got to do 25 over 16. But, in order to do 25, you got to borrow from the 11, right? So, that turns that into a 10. Easy day. So, let's rewrite all of this and we got 10 and 25/16 5 and 10/6 16.

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