解
0.125×72
=0.125×8×9
=1×9
=9
3.2×2.5
=8×0.4×2.5
=8×1
=8
0.93×99
=0.93×(100-1)
=0.93×100-0.93×1
=93-0.93
=92.07
70.1×9.9
=70.1×(10-0.1)
=70.1×10-70.1×0.1
=701-7.01
=693.99
0.93+9.9
=(1-0.1)+0.93
=(1+0.93)-0.1
=1.93-0.1
=1.83
6.4×(0.125+12.5)
=6.4×0.125+6.4×12.5
=0.8×8×0.125+8×0.8×12.5
=0.8×1+8×1
=8+0.8
=8.8