About this video
The video works out 2/5 divided by 7/3. It rewrites the division as multiplying by the reciprocal, 3/7, then multiplies numerators and denominators to get 6/35.
You'll be able to
- rewrite dividing by a fraction as multiplying by its reciprocal.
- multiply two fractions by multiplying the numerators and the denominators.
Key words
- reciprocal
- The fraction you get by swapping the numerator and denominator, so the reciprocal of 7/3 is 3/7.
- numerator
- The top number of a fraction.
- denominator
- The bottom number of a fraction.
Transcript
So let's calculate what 2/5 divided by 7/3 is, and I encourage you to pause this video and try to calculate this on your own. Well we just have to remind ourselves that this is going to be the exact same thing as 2 over 5 times the reciprocal of 7/3, which is 3 over 7.
And then multiplying two fractions is pretty straightforward. This is just going to be equal to the product of the numerators. So 2 times 3 over the product of the denominators, over 5 times 7-- I'm trying to keep the colors consistent-- which of course is going to be equal to 2 times 3 is equal to 6.
And 5 times 7-- I'll do this in a new color, let's see, I haven't used this shade of blue yet-- 5 times 7 of course is equal to 35. So this is equal to 6/35.
Video © Khan Academy, used under CC BY-NC-SA. Watch on Khan Academy. Puzzicle is not affiliated with Khan Academy.