(1988+1986+1984+…+6+4+2)-(1+3+5+…+1983+1985+1987)
问题描述:
(1988+1986+1984+…+6+4+2)-(1+3+5+…+1983+1985+1987)
答
(1988+1986+1984+…+6+4+2)-(1+3+5+…+1983+1985+1987),
=(1988-1987)+(1986-1985)+…(4-3)+(2-1),
=1+1+…1+1,
=1×(1988÷2),
=994.