计算:1-2+3-4+5-6+7-8+…+4999-5000.

问题描述:

计算:1-2+3-4+5-6+7-8+…+4999-5000.

原式=(1-2)+(3-4)+(5-6)+(7-8)+…+(4999-5000)
=-1-1-1-1…-1
=-1×2500
=-2500.