2100÷42=2100÷21÷2=100÷2=50
结合律.列式为:210042=2100(7x6)=210076=3006=50
答:2100÷42=2100X2/42/2=50
2100÷42=2100÷7÷6=300÷6=5025x64x125=(25x4)x2x(8x125)=100x2x1000=200000
2100/21/2=50
2100÷42=(2100÷7)÷(42÷7)=300÷6=50
2100÷42=2100÷7÷6=300÷6=50
向左转|向右转
2100除42=21*100除(21*2)=100除2=50
2100÷42用巧算2100÷42=(2100÷21)÷(42÷21)=100÷2=50