42X119+42 38X8+16 99X52 用乘法分配律来计算怎么写?

Question

如题所述

Answer 1

　42X119+42
=42×119+42×1
=42×(119+1)
=42×120
=42×(100+20)
=42×100+42×20
=4200+840
=5040
38X8+16
=38×8+8×2
=8×(38+2)
=8×40
=320
99X52
=(100-1)×52
=100×52-52×1
=5200-52
=5148