Multiply a number by 8, divide it by 2, and subtract 20. The result is 100. What's the number?

Multiply a number by 8, divide it by 2, and subtract 20. The result is 100. What's the number?

This number = (100 + 20) × 2 △ 8
=120×2÷8
=240÷8
=30

Add 5 to a number, multiply by 5, subtract 5 and divide by 5. The final result is 5
Solution of a series of equations

Let this number be X
[（x+5)*5-5]/5=5
（x+5）*5-5=25
（x+5)*5=30
x+5=6
x=1

If you add 5 to a number, multiply by 5, divide by 5, and then subtract 5, the difference is still 5
fast

Let this number be X
Plus 5 is (x + 5)
Multiply by 5, that is (x + 5) △ 5 × 5
Subtracting 5 is (x + 5) △ 5 × 5-5
Difference or 5, i.e. (x + 5) △ 5 × 5-5 = 5
Because if you multiply by 5 and divide by 5, you don't multiply and divide
We get x + 5-5 = 5
One plus one minus, x = 5

If you add 5 to a number, multiply by 5, subtract 5, and divide by 5, the result is 5. This number is 5______ ．

(5 × 5 + 5) △ 5-5, = (25 + 5) △ 5-5, = 30 △ 5-5, = 6-5, = 1

The sum of the three remainders obtained by removing 63, 91129 from the natural number n is 25, then n is?

∵ 63 + 91 + 129-25 = 258258 = 2 × 3 × 43, ∵ this number may be: 2, 3, 43, 6, 86, 129; and ∵ this number should be less than 63, greater than 25, ∵ this number can only be 43

The sum of the three remainders obtained by removing 63, 91129 from the natural number n is 25, then n is?

∵ 63 + 91 + 129-25 = 258258 = 2 × 3 × 43, ∵ this number may be: 2, 3, 43, 6, 86, 129; and ∵ this number should be less than 63, greater than 25, ∵ this number can only be 43

A natural number, use it to remove 63, 91, 129, the sum of the three remainder is 28
63+91+129-28=255
255=3*5*17
Why do you do this? Why do you add up the divisor and subtract 28?

Because the sum of 63 + 91 + 129 - 28 can be divided by this natural number
255 = 3 * 5 * 17 decompose 255 into prime factor, because the sum of remainder is 28, this natural number cannot be 3 or 5
So the natural number is 17

There is such a natural number. If you use it to remove 63, 91, 129, the sum of the three remainder numbers is 28. What is the natural number?

63+91+129=283
283-28=255
28 ÷ 3 = 9 more than 1
This natural number, which is a divisor of 255, is smaller than 63
It is larger than 10 (otherwise, the sum of the three residues is 9 × 3 = 27)
255=3×5×17
The divisors satisfying the requirements are 15, 17 and 51
Check it out. Only 17 of them fit
So the natural number is 17

There is a natural number. If you use it to remove 63, 91 and 129, the sum of the three remainders is 25. This natural number is（

The answer is 43
63+91+129-25＝258＝2×3×43
Because the sum of the remainder is 25, and the remainder cannot be greater than the divisor, the divisor cannot be 2 or 3, so it can only be 43

1+1234.768534=?

1+1234.768534=1235.768534