beabigtree.com
当前位置:首页>>关于82乘以78的巧算的资料>>

82乘以78的巧算

426*78=33228

77十78十79十80十81十82十83=77+3+78+2+79+1+80+81-1+82-2+83-3=(77+3)+(78+2)+(79+1)+80+(81-1)+(82-2)+(83-3)=80+80+80+80+80+80+80=80*7=560

89*78=(80+9)(80-2)=80^2+80*(9-2)-18=6400+560-18=6942

72*78=(70+2)*(70+8)=70*70+2*70+8*70+2*8=70*(70+2+8)+2*8=70*80+2*8=5600+16=5616 记住,这样首位相同,个位相加等于10的数相乘,就是这样:72*78=70*80+2*8=5600+16=5616 这种叫做“同头尾合十”.

83+82+78+79+80+81+79+77=(83+77)+(82+78)+(79+81)+79+80=160+160+160+159=480+159=639 谢谢,请采纳

78+76+83+82+77+80+79+85,=(80-2)+(80-4)+(80+3)+(80+2)+(80-3)+80+(80-1)+(80+5),=80*8+(3+2+5-2-4-3-1),=640.

78*7878

=25*(80-2)-78=25*80-25*2-78=2000-50-(80-2)=1950-80+2=1870+2=1872

80*78/79=(79+1)*(79-1)/79=(79^2-1)/79=79-1/79=78又78/79

84*21+84*78+84=84*(21+78+1)=84*100=8400

mcrm.net | dzrs.net | gmcy.net | rtmj.net | dkxk.net | 网站首页 | 网站地图
All rights reserved Powered by www.beabigtree.com
copyright ©right 2010-2021。
内容来自网络,如有侵犯请联系客服。zhit325@qq.com