Problem 16
Statement
2¹⁵ = 32768 and the sum of its digits is 3 + 2 + 7 + 6 + 8 = 26.
What is the sum of the digits of the number 2¹⁰⁰⁰?
Solution
The code, in C.
#include <stdio.h>
long long int sumExp(int e){
int i,j,a[400]={2,0};
long long int k=0;
for(i=1;i<e;i++){
for(j=0;j<400;j++)
a[j]*=2;
for(j=1;j<400;j++){
a[j]+=a[j-1]/10;
a[j-1]%=10;
}
}
for(i=399;i>=0;i--)
k+=a[i];
return k;
}
int main(void){
printf("%lld\n",sumExp(1000));
}
Answer
1366
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