简便运算5+55+555+5555+55555=?
问题描述:
简便运算5+55+555+5555+55555=?
答
5*5 +50*4 +500*3 +5000*2 +50000
=25 +200 +1500 +10000 +50000
=61725
或者:
5+55+555+5555+55555
=5 + 5*11 +5*111 +5*1111 +5*11111
=5*(1+11+111+1111+11111)
=5*12345
=61725