**The Program in C that counts the number of digits in a given number is given below:**

```
#include <stdio.h>
#include <math.h>
int main() {
int n;
printf("Enter a number: ");
scanf("%d", &n);
int count = (int)log10(n) + 1;
printf("Number of digits: %d", count);
return 0;
}
```

## Output:

Enter a number: 9999999999

Number of digits: 10

## Pro-Tips**💡**

In this program, the log10 function returns the base 10 logarithm of the given number.

Since log10 of a number n gives the number of digits in n – 1, we add 1 to it to get the number of digits. The final result is casted to int as the log10 function returns a double.

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