Lesson 5 -1:
A benchmark is a number that is easy to use when you estimate. When estimating the sums and differences of fractions, we use the benchmarks 0, ½, and 1. (another chart on page 249 in textbook)
Change each fraction to 0, ½, or 1. Add or subtract ½ 0= ½
½ ½ = 1
If you have mixed numbers, then round the fraction part up to 1 or down to 0. If the fraction is greater than ½, then round up to 1. If it is less than ½, then round down to 0.
= 6