Question

用简便方法计算下面的题:12.5✘8.7,2.5✘4.4-2.5✘0.4，5.24+5.24✘99

Answer 1

12.5×8.7
=12.5×(8+0.8-0.1〉
=12.5×8+12.5×0.8-12.5×0.1
=100+10-1.25
=108.75

Answer 2

12.5×8.7
=12.5×(8+0.8-0.1)
=100+10-1.25
=109.75
2.5×4.4-2.5×0.4
=2.5×(4.4-0.4)
=2.5×4=10
5.24+5.24×99
=5.24×(1+99)
=5.24×100=524

Answer 3

2.5×4.4-2.5×0.4=2.5×(4.4-0.4)=2.5×4=10
5.24+5.24×99=5.24×(99+1)=524
12.5×8.7=8.7×10+8.7×2+8.7×0.5
=87+17.4+4.35=108.75
12.5×8.7=12.5×8+12.5×0.7=100+8.75=108.75