Question

Let $S(n)$ represents the sum of digits of a natural number $n$. For example, $S(128) = 1 + 2 + 8 = 11$. What is the value of $S(2^6 	imes 3^4 	imes 5^5)$?

Accepted Answer

A. Calculate the value of the number: $$2^6 	imes 3^4 	imes 5^5 = (2^5 	imes 5^5) 	imes 2^1 	imes 3^4 = 10^5 	imes 2 	imes 81 = 162 	imes 10^5 = 16200000$$ Sum of digits $S(16200000) = 1 + 6 + 2 + 0 + 0 + 0 + 0 + 0 = 9$.

Sum of Digits of an Expression

Explanation

Practise this under exam conditions