125*165用乘法巧算怎么解
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125*165用乘法巧算怎么解
125*165用乘法巧算怎么解
125*165用乘法巧算怎么解
125*165
=125*(100+64+1)
=125*(100+8*8+1)
=125*100+125*8*8+125*1
=12500+8*1000+125
=12500+8000+125
=20500+125
=20625.
165=80+80+5
用125分别乘
125*165=(145-20)*(145+20)=145²-20²=21025-400=20625
或者125*165=125*(160+5)=125*160+125*5=5*25*4*40+125*5=5*100*4+625=20000+625=20625
原式=125(125+40)=25*25*25+5000=625*25+5000
=(600+25)*25+5000=15000+625+5000=20625
=125*(100+8*8+1)
=125*100+125*8*8+125*1
=12500+8*1000+125
=12500+8000+125
=20500+125
=20625.