Idea 17of 24Builds onMultiply the top and bottom by the same numberSame bottom number: compare the tops
Rename to the same bottom number to compare
How do you compare 2/3 and 3/4 exactly?
Today you'll discover
- how to find a bottom number both fit
- how to rename each fraction
- how to compare close fractions
Think first2/3 and 3/4 are close
Which is greater: 2/3 or 3/4?
Decide first, then press Next. Find one size of part that fits both.
Two strips the same length, in thirds and fourths, named 2/3 and 3/4. Then each is shown above a strip in twelfths, shaded 8/12 and 9/12, with dashed lines where the shading ends. The last step shows strips for 3/5, 6/10 and 7/10.
See the whole ideathe big idea and the key word, in one place
The big idea
Rename both fractions with a common denominator, then compare the numerators.
Step by step2/3 and 3/4 in twelfths: 2/3 = 8/12 and 3/4 = 9/12. 8 < 9, so 2/3 < 3/4.
Easy to get wrongMultiply the top too. 2/3 = 8/12, not 2/12: every third becomes 4 twelfths.
Key word
- common denominator
- a bottom number that two fractions can both be renamed to, like 12 for thirds and fourths
Ready to use it?
- Rename two fractions with a common denominator.
- Compare fractions with different denominators.