Question

99×42+42怎样用脱式简便运算？

Answer 1

这个只要把42看成42×1，所以原式=99×42+42×1=42×（99+1）=42×100=4200

Answer 2

99*42+42=(99+1)*42=100*42=4200

Answer 3

99×42+42=42×（99+1）=4200

Answer 4

99×42+42
=（99+1）×42
=100×42
=4200