There are 90 scores: 1 / 2, 1 / 3, 1 / 4, 1 / 5 1 / 90, 1 / 91, can you pick out 10 of them and add a sign to make their sum equal to - 1? There are 90 scores: 1 / 2, 1 / 3, 1 / 4, 1 / 5 1 / 90, 1 / 91, can you pick out 10 of them and add a sign to make their sum equal to - 1? Write down 10 numbers

There are 90 scores: 1 / 2, 1 / 3, 1 / 4, 1 / 5 1 / 90, 1 / 91, can you pick out 10 of them and add a sign to make their sum equal to - 1? There are 90 scores: 1 / 2, 1 / 3, 1 / 4, 1 / 5 1 / 90, 1 / 91, can you pick out 10 of them and add a sign to make their sum equal to - 1? Write down 10 numbers

-1/2-1/3-1/4+1/12=-1
The remaining two adjacent numbers are subtracted, such as 1 / 5-1 / 6 + 1 / 30 = 0 1 / 7-1 / 8 + 1 / 56 = 0 1 / 9-1 / 10 + 1 / 90 = 0
-1/2-1/3-1/4+1/12+1/5-1/6+1/30+1/7-1/8+1/56+1/9-1/10+1/90=-1