Question

李老师到市场买肉,每斤6.5元,买了5.5斤,他很快算出应付的钱数,给卖肉的35.75元,卖肉的人用笔算很长时间,说对.

Answer 1

6.5*5.5

=(6-0.5)(6+0.5)

=6^2-0.5^2

=36-0.25

=35.75(元）

望采纳