Calculation: now there are 90 Egyptians, 1 / 2, 1 / 3 1 / 91, select 10 of them, add the sign to make the sum of them equal to - 1? | Math enthusiast | Mathematical art

Calculation: now there are 90 Egyptians, 1 / 2, 1 / 3 1 / 91, select 10 of them, add the sign to make the sum of them equal to - 1?

1/3+1/4+…… +So it's like 1 / 2 + 1 / 3 + 1 / 91 can never be equal to 1. I don't think there is a solution to this problem. If there is a solution, please let me know. Thank you

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1. 1 / 2, 1 / 3, 1 / 4, 1 / 5... 1 / 90, 1 / 91, choose 10 numbers from them, add a sign to make the sum equal to - 1
2. 1/2,1/3,1/4,1/5,…… 1 / 90, 1 / 91, pick out ten numbers, add the sign, and their sum is - 1
3. What symbol in the middle of 9 7 5 4 is equal to 24 9 7 5 4 is equal to 24
4. 5 what 5 what 5 what 5 what 5 equals 9
5. Five nines with appropriate symbols are 73
6. According to the requirement of operation result, add operation symbol and bracket 1 / 20.43/101/50.1 = 100.30.30.30.30.30.3 = 0 0.3 0.3 0.3 0.3 0.3=1 0.3 0.3 0.3 0.3 0.3=2 0.3 0.3 0.3 0.3 0.3=4
7. 1 what, 2 what, 3 what, 4 what, 5 what = 10 with appropriate operation symbols and brackets
8. 1, 2, 3, 4, 5 = 4 can be added with operation symbols in brackets
9. Do you want to change symbols when moving items? Like 3x-7 + 7 = 3-2x-6, I'm bad at math. I don't know anything about symbols
10. What is the law of the sign change of mathematics without bracket in the first volume of junior high school
11. There are 90 Egyptian numbers, there are 90 Egyptian numbers, 1 / 2, 1 / 3, 1 / 4,..., 1 / 90, 1 / 91. Choose ten of them and add the sign to make them equal to - 1
12. 90 Egyptians: 1 / 2, 1 / 3, 1 / 4, 1 / 5 , 1 / 90, 1 / 91, select 10, add positive and negative signs, so that the sum of them is - 1
13. 2/1,3/1,4/1,5/1,… 90 / 1, 91 / 1, you can pick out 10 of them and add a sign to make their sum equal to - 1
14. 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
15. Egypt, like China, is one of the four ancient civilizations. Ancient Egyptians only used scores with numerator 1, such as 1 / 3 + 1 / to represent 2 / 5, 1 / 4 + 1 / 7 + 1 / 28 to represent 3 / 7, and so on. Now there are 90 Egyptian scores: 1 / 2, 1 / 3, 1 / 4, 1 / 5,... 1 / 90, 1 / 91. Can you pick out 10 of them, plus the sign, is their sum equal to - 1?
16. How can 123456789 be equal to 2 with addition and subtraction
17. 123456789 is equal to 24 by addition and subtraction
18. 123456789 is not used. Multiplication and division can only be added and subtracted. The number should be in order. The result is ten
19. 6, 6, 6, 6, 6, is equal to 7
20. What is the sign of seven sixes and the result is 600?