小学3年级数学 简便计算.ppt

文档介绍：987-178-222
=987-(178+222)
=987-400
=587
325+46-125+54
=(325-125)+(46+54)
=200+100
=300
=325-125+46+54
567-558-562-555+563
=(567+563)-(558-562)-555
=1130+1120+555
=2250+555
=2805
67×12+67×35+67×52+67
=67×(12+35+52+1)
=67×100
=67×12+67×35+67×52+67×1
=6700