C Exercises: Check whether a given number is within 2 of a multiple of 10

Last update on July 28 2025 12:50:13 (UTC/GMT +8 hours)

21. Near Multiple of 10 Check

Write a C program to check whether a given number is within 2 of a multiple of 10.

C Code:

#include <stdio.h> // Include standard input/output library
#include <stdlib.h> // Include standard library for additional functions

// Function declaration for 'test' with an integer parameter 'n'
int test(int n);

int main(void){
    // Print the result of calling 'test' with different integer values and format the output
    printf("%d",test(3));
    printf("\n%d",test(7));
    printf("\n%d",test(8));
    printf("\n%d",test(21));
}

// Function definition for 'test'
int test(int n)
{
    // Check if the last digit of 'n' is less than or equal to 2 OR greater than or equal to 8
    if (n % 10 <= 2 || n % 10 >= 8) {
        return 1; // If the condition is true, return 1 (true)
    } else {
        return 0; // If the condition is false, return 0 (false)
    }
}

Sample Output:

Explanation:

int test(int n) {
  return n % 10 <= 2 || n % 10 >= 8;
}

The above function takes an integer n as input and returns 1 if the remainder of n divided by 10 is less than or equal to 2 or greater than or equal to 8, and 0 otherwise.

Time complexity and space complexity:

The time complexity of the function is O(1) as it performs a constant number of operations regardless of the input value.

The Space complexity of the function is O(1) as it uses a constant amount of space regardless of the input value.

Flowchart:

For more Practice: Solve these Related Problems:

Write a C program to check if a given number is within 3 of a multiple of 15.
Write a C program to verify if a number is within 1 of a multiple of 8.
Write a C program that checks if an integer is within 2 of a multiple of 12.
Write a C program to determine if a number is within 5 of a multiple of 20.

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