99×41/42×21 简便方法,
问题描述：
99×41/42×21 简便方法,
答
99×(41/42)×21 简便方法
解,得：
==11*3(41/21)*21
==11*3*41
==(10+1)*123
==1230+123
==1353
99×41/42×21