7900÷25=(7900x4)/(25x4)=31600/100=316
24000÷125=(24000x8)/(125x8)=192000/1000=192
3200÷64=(3200x5)/(64x5)=3200x5/320=50
4600÷20÷5=4600/(20x5)=4600/100=46
2800÷{28x25}=2800/28/25=100/25=4
15000÷125÷15=15000/15/125=1000/125=8 /表示除号