Posted by Julie on Monday, October 12, 2009 at 7:22pm.
Benchmark numbers are easier to add-usually ending in 0's or 5's.
Ex:
28+31 can be turned into 30+30. 28 was rounded up to 30, and 31 was rounded down to 30.
4 and lower is rounded down; 5 and higher is rounded up. If the number is 3,4,5,6 or 7 it is rounded to five, if you're getting more specific.
I hope this helps; but I'm only in 6th grade so I'm not sure (:
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