一道数学题、 551+552+553+554+555+556+557=( ) * ( ) = ( )
问题描述:
一道数学题、 551+552+553+554+555+556+557=( ) * ( ) = ( )
答
551+557=2*554 552+556=2*554 553+555=2*554 原式=554*7=3878
答
=(554-3)+(554+3)+(554-2)+(554+2)+(554-1)+(554+1)+554
=554*7
=3878
答
=7*554=3878