Question

If (NN)^3 = 8518N, what digit does N represent?

(A) 1

(B) 2

(C) 4

(D) 5

(E) 6

Answer 1

(C) 4

Explanation:

I am going to solve this by trial and error:

(A) 1

Is:
`(11)^(3) = 85181`?

`(11)^3 = 1331`

So 1 is not the digit of N.

(B) 2

Is:
`(22)^(3) = 85182`?

`22^3 = 10648`

So 2 is not the digit of N.

(C) 4

Is:
`(44)^(3) = 85184`?

`44^3 = 85184`

Correct, so the answer is c.

(D) 5

`55^3 = 166375 \\eq 85185`

(E) 6

`66^3 = 287496 \\eq 85186`