Solution to: Plus & Minus

There are 11 different ways:

123 + 45 - 67 + 8 - 9 = 100
123 + 4 - 5 + 67 - 89 = 100
123 - 45 - 67 + 89 = 100
123 - 4 - 5 - 6 - 7 + 8 - 9 = 100
12 + 3 + 4 + 5 - 6 - 7 + 89 = 100
12 + 3 - 4 + 5 + 67 + 8 + 9 = 100
12 - 3 - 4 + 5 - 6 + 7 + 89 = 100
1 + 23 - 4 + 56 + 7 + 8 + 9 = 100
1 + 23 - 4 + 5 + 6 + 78 - 9 = 100
1 + 2 + 34 - 5 + 67 - 8 + 9 = 100
1 + 2 + 3 - 4 + 5 + 6 + 78 + 9 = 100

Remark: if it is not only allowed to put plus signs and minus signs between the digits, but also in front of the first 1, then there is a twelfth possibility: - 1 + 2 - 3 + 4 + 5 + 6 + 78 + 9 = 100.

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