Scribe Post #3
Learning Target: Estimate sums and differences with fractions.
Lesson: To estimate a sum, round the fraction first. (You would round it up if it is 1/2 or greater, and down if it was less.) Then estimate the sum.
To estimate a difference, round the fraction first. (You would round it up if the fraction is 1/2 or greater, and down if it was less.) Then estimate the difference.
Example: (Sum)
12 7/8
+ 15
~ 28
1. Round 7/8 up because it is more than 1/2. 2. Estimate the sum of the numbers.
Example: (Difference)
16 2/9
- 10
~6
1. Round 2/9 down because it is less than 1/2. 2. Estimate the difference of the numbers.
Links:
Estimating sums and differences with fractions
Comments: 1
You made one mistake: Unlike whole numbers, when a fraction is greater than 1/2 (or 5 with whole numbers), we don't necessarily round up. We have to make sure the fraction is closer to the whole number than it is to 1/2. Ditto for rounding down.
Mr. Tubbs
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