Math Question?

Question

A digital sum of a number is found by adding all of the digits of a number, then adding all the digits of that number, and so on, until you are left with a one-digit number.

For example, the digital sum of the number 729 would be found like this: 7+2+ 9 = 18, and then 1+ 8 = 9.

What is the digital sum of the number that can be found by the following formula?

(9[62773] + 2)[83721]

PS - The numbers in brackets are smaller and higher up on the math problem.

Why would you post that here? "Not interested in math"? I need an answer not an opinion of weather or not you like math.

Don't do math on weekends? Me neither + I am not good at math..

Thanks, I think I will put 8, considering you have answered a lot in math questions. :)

Answer 1

9 raised to whatever power always has a digital sum of 9.
9^1 = 9
9^2 = 81 = 9
9^3 = 729 = 18 = 9
(btw, the last equal signs simply denote the digital sums...)

thus this question is now the same as asking the digital sum of

(9 + 2)[83721]
= 11[83721]

11 has a digital sum of 2.
2^1 = 2
2^2 = 4
2^3 = 8
2^4 = 16 = 7
2^5 = 32 = 5
2^6 = 64 = 10 = 1
2^7 = 128 = 2

thus the power of 2 has a cyclic digital sum... the length of the cycle is 6.

11[83721] = 11[6*13953 + 3]
thus this has the same digital sum as 2^3

the answer is 8.


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Answer 2

How you solve depends on how you interpret the instructions. Not too clear what you mean by "smaller and higher up" . I assumed you meant that the digital sum ranks first in the order of operations (second method). Even if this is not the case, fortunately I arrive at the same answer regardless of method.

In the first method I solve the problem as any other math problem then acquire the digital sum of the final answer.

(9[62773] + 2)[83721]
=(564957 + 2)83721
=(564959)83721
= 47298932439
= 60
= 6

In the second approach, I acquire the digital sums of the numbers in the brackets, solve the problem as any other math problem, and then acquire the digital sum of that final answer.

(9[62773] + 2)[83721]
=(9[25]+2)[21]
= (9*7 +2)3
= (63+2)3
= 65*3
= 195
= 15
= 6

Answer 3

my answer

9[62773] = 564957
and
(9[62773] + 2) = 564959

(9[62773] + 2)[83721] = 47298932439

so the digital sum of 47298932439 will be
4+7+2+9+8+9+3+2+4+3+9 = 60

Answer 4

Please confirm the brackets.

Is it 9 to the power of 62773 plus 2, and that sum to the power of 83721.

Or 9 to the power 62773 plus 2 to the power 83721 ?

Answer 5

The answer is definitely 8.

Answer 6

9x62773=564957+2=564959

564959x83721=4.729893244 x 10^10

Using method of addinng digits until just one digit is left.

I came up with 7

Hope this helps