69x78+39x62怎么巧算

2026年09月22日 13:10
有2个网友回答
网友(1):

69x78+39x62
=69x78+39x2x62/2
=69x78+78x31
=78x(69+31)
=78x100=7800

网友(2):

69x78+39x62
=69x78+78x31
=(69+31)x78
=100x78
=7800