suggest a solution
    N = power(5 , 1!+2!+3!+...+12!+13!) where 5 is base and next value is the index

The digits of the number N are added to get another number. Then the digits of the number obtained are added to get yet another number. The process is repeated till a single digit number is obtained. What is that single digit number? (Please explain the complete process by which you arrive at the answer). Please do not suggest to find the sum of the factorials and find the value of 5 raised to sum. Instead, no calculator is allowed

Mridul
suggest a solution
===

    N = power(5 , 1!+2!+3!+...+12!+13!) where 5 is base and next value is the index

The digits of the number N are added to get another number. Then the digits of the number obtained are added to get yet another number. The process is repeated till a single digit number is obtained. What is that single digit number? (Please explain the complete process by which you arrive at the answer). Please do not suggest to find the sum of the factorials and find the value of 5 raised to sum. Instead, no calculator is allowed

Mridul