104*2.5
=(100+4)×2.5
=100×2.5+4×2.5
=250+10
=260
1.25*(4-0.8)
=1.25×4-1.25×0.8
=5-1
=4
4.2*0.5-1.6*0.52
=2.1-0.832
=1.268
12.5*32*0.25
=12.5×8×4×0.25
=100×1
=100
0.48*99+0.48
=0.48×(99+1)
=0.48×100
=48
63*10.1
=63×(10+0.1)
=63×10+63×0.1
=630+6.3
=636.3