1 (-7)+(+12)+(-13)=
2 0.72+0.02-0.7+(-0.01)=
3 (-1/3)+(1/2)+(-2/3)+(+4/5)+(-1/2)
4 (-3/1)+(+2/1)+(-3/2)+(+5/4)+(-2/1)
5 (+0.25)+(-3.4)+(+5.1)+(-1.8)
6. 1+(-2)+3+(-4)+5+(-6)+.......+99+(-100)
參考答案:1、(-7)+(+12)+(-13)= -7+12-13=-8
2 0.72+0.02-0.7+(-0.01)= 0.03
3 (-1/3)+(1/2)+(-2/3)+(+4/5)+(-1/2) =-1/3-2/3+1/2-1/2+4/5=-1/5
4 (-3/1)+(+2/1)+(-3/2)+(+5/4)+(-2/1)
=-13/4
5 (+0.25)+(-3.4)+(+5.1)+(-1.8) =0.15
6. 1+(-2)+3+(-4)+5+(-6)+.......+99+(-100)=（-1）*50=-1
1-2=-1 3-4=-1.....