Question

计算（能简算的要简算） 0.39×199（ 12.5-1.

计算（能简算的要简算） 0.39×199（ 12.5-1.25）×85.6×6.5-5.6×5.53.65×10.156.5×99+56.556.5×99．

Answer 1

①0.39×199
=0.39×（200-1）
=0.39×200-0.39×1
=78-0.39
=77.61

②（ 12.5-1.25）×8
=12.5×8-1.25×8
=100-10
=90

③5.6×6.5-5.6×5.5
=5.6×（6.5-5.5）
=5.6×1
=5.6

④3.65×10.1
=3.65×（10+0.1）
=3.65×10+3.65×0.1
=36.5+0.365
=36.865

⑤56.5×99+56.5
=56.5×（99+1）
=56.5×100
=5650

⑥56.5×99
=56.5×（100-1）
=56.5×100-56.5×1
=5650-56.5
=5593.5