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int var = 12837;
// Gets fourth digit, divide by 100 instead of 1000 to get third etc
int fourthDigit = (millis() / 1000) % 10;
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#include <iostream>
#include <math.h>
using namespace std;
int main(){
unsigned long long n = 2345423454234542345 ; // the number n
int x = floor(log10(n)) + 1 ; // x = the digit count,
cout << x << endl ; // the largest digit can be handled with
// is unsigned long long
return 0;
}