9 8 7 6 5 4 3 2 1 = 20 (only add and subtract) Four mathematical talents PHS

9 8 7 6 5 4 3 2 1 = 20 (only add and subtract) Four mathematical talents PHS

9+8-6+5+4-3+2+1=20

How to add the plus and minus sign to 1,2,3,4,5,6,7,8,9 is equal to 20
Only plus and minus signs can be added How to add it

There are 5 odd numbers from 1 to 9. The sum and difference of odd numbers and odd numbers are even numbers. The sum and difference of even numbers and odd numbers are odd numbers, and the sum and difference of even numbers and even numbers are even numbers. If you only fill in the plus and minus sign, the final result is odd number, not even number 20

1.2.3.4.5.6.7.8.9 use two minus signs, one plus a bracket, the order is unchanged, the number is 100

(123-45-67)+89=100
I feel the brackets are a little redundant

The result of I using 1 23 4 5 6 7 8 9 is that 30 people only fill in addition and subtraction, not fill in multiplication and division and brackets
1 + 2 + 3 + 4 + 5 + 6-7-8 + 9 equals 30

6+7+8+9-3+1+4-2=30