(探究创新题)计算3620-1-2-3...-76-77-78-79

问题描述:

(探究创新题)计算3620-1-2-3...-76-77-78-79

3620-1-2-3...-76-77-78-79
=3620-(1+2+3...+76+77+78+79)
=3620-〔(1+79)+(2+78)+(3+77)+...+(39+41)+40〕
=3620-(39*80+40)
=460