1+2-3+4+5-6+7+8-9……97+98-99
=(1+2-3)+(4+5-6)+....+(97+98-99)
=0+3+6+.....+96
=(3+96)X[(96-3)÷3+1]÷2
=99X32÷2
=100X16-1X16
=1600-16
=1584
1+2-3+4+5-6+7+8-9+......+97+98-99
=(1+2-3)+(4+5-6)+(7+8-9)+...+(97+98-99)
=0+3+6+9+...+96
=(0+96)×[(96-0)÷3+1]÷2
=96×33÷2
=1584
我们都知道1加到100=5050,你现在就是5050-100-99=4851
1+2-3+4+5-6+7+8-9……97+98-99
=(1+2-3)+(4+5-6)+(7+8-9)+…+(97+98-99)
=0+3+6+9+…+96
=3×(1+2+3+4+…+31+32)
=1584