Idea 21of 24Builds onAdd fractions with the same bottom numberFractions that make one whole
Subtract fractions with the same bottom number
What is 1 − 3/8?
Today you'll discover
- how to write 1 as eighths
- why the bottom number stays
- how far apart two fractions are
Think firstA full bottle of juice; 3/8 is poured out
How much of the bottle is left?
Decide first, then press Next. Write the whole in the same parts first.
A full bottle bar of eight eighths, and a bar showing the three eighths poured out. The eighths are counted, the poured ones fade, and five eighths slide into a bottom bar marked left. Then 8/8 − 3/8 = 5/8 is written. The last step compares Ken's seven tenths of a kilometre with Ana's four.
See the whole ideathe big idea and the key word, in one place
The big idea
To subtract fractions with like denominators, subtract the numerators and keep the denominator.
Easy to get wrongTo take a fraction from 1, write 1 with the same bottom number first: 1 − 3/8 = 8/8 − 3/8.
In a storyPractice is 3/4 of an hour and 1/4 of an hour is done. 3/4 − 1/4 = 2/4 of an hour is left.
Key word
- difference
- the answer to a subtraction: how much is left, or how far apart two amounts are
Ready to use it?
- Subtract fractions with like denominators.
- Take a fraction away from 1 whole.