# Check if a large number is divisible by 6 or not

Given a number, the task is to check if a number is divisible by 6 or not. The input number may be large and it may not be possible to store even if we use long long int.

Examples:

```Input  : n = 2112
Output: Yes

Input : n = 1124
Output : No

Input  : n = 363588395960667043875487
Output : No```

## C++

 `#include ` `using` `namespace` `std; ` ` `  `int` `main() { ` ` `  `    ``long` `n = 36358839596; ` `   `  `      ``// finding given number is divisible by 6 or not ` `    ``if` `(n % 6 == 0) ` `        ``cout << ``"Yes"``; ` `    ``else` `        ``cout << ``"No"``; ` `    ``return` `0; ` `} ` ` `  `// This code is contributed by lokesh`

## Java

 `// Java code for the above approach ` `// To check whether the given number is divisible by 6 or not ` `import` `java.io.*; ` ` `  `class` `GFG { ` `    ``public` `static` `void` `main (String[] args) { ` `        ``long` `n = 36358839596L; ` `  `  `        ``// finding given number is divisible by 6 or not ` `        ``if` `(n % ``6` `== ``0``) ` `              ``System.out.print(``"Yes"``); ` `        ``else` `              ``System.out.print(``"No"``); ` `    ``} ` `} ` ` `  `// This code is contributed by lokesh`

## Python3

 `# Python code  ` `# To check whether the given number is divisible by 6 or not ` ` `  `#input  ` `n``=``363588395960667043875487`  `# the above input can also be given as n=input() -> taking input from user ` `# finding given number is divisible by 6 or not ` `if` `int``(n)``%``6``=``=``0``: ` `  ``print``(``"Yes"``)  ` `else``:  ` `  ``print``(``"No"``)`

## C#

 `using` `System; ` `public` `class` `GFG { ` ` `  `  ``static` `public` `void` `Main() ` `  ``{ ` ` `  `    ``// C# code for the above approach ` `    ``// To check whether the given number is divisible by 6 or not ` ` `  `    ``//input ` `    ``long` `n = 36358839596; ` ` `  `    ``// finding given number is divisible by 6 or not ` `    ``if` `(n % 6 == 0) ` `      ``Console.Write(``"Yes"``); ` `    ``else` `      ``Console.Write(``"No"``); ` ` `  `  ``}  ` `} ` ` `  `// This code is contributed by ksrikanth0498`

## Javascript

 ``

## PHP

 ` `

Output

`No`

Time complexity: O(1) as it is performing constant operations
Auxiliary Space: O(1) as it is using constant space for variables

Since input number may be very large, we cannot use n % 6 to check if a number is divisible by 6 or not, especially in languages like C/C++. The idea is based on following fact.

```A number is divisible by 6 it's divisible by 2 and 3.
a)  A number is divisible by 2 if its last digit is divisible by 2.
b)  A number is divisible by 3 if sum of digits is divisible by 3.```

Below is the implementation based on above steps.

## C++

 `// C++ program to find if a number is divisible by ` `// 6 or not ` `#include ` `using` `namespace` `std; ` ` `  `// Function to find that number divisible by 6 or not ` `bool` `check(string str) ` `{ ` `    ``int` `n = str.length(); ` ` `  `    ``// Return false if number is not divisible by 2. ` `    ``if` `((str[n-1]-``'0'``)%2 != 0) ` `       ``return` `false``; ` ` `  `    ``// If we reach here, number is divisible by 2. ` `    ``// Now check for 3. ` ` `  `    ``// Compute sum of digits ` `    ``int` `digitSum = 0; ` `    ``for` `(``int` `i=0; i

## Java

 `// Java program to find if a number is ` `// divisible by 6 or not ` `import` `java.io.*; ` `class` `IsDivisible ` `{ ` `    ``// Function to find that number divisible by 6 or not ` `    ``static` `boolean` `check(String str) ` `    ``{ ` `        ``int` `n = str.length(); ` `      `  `        ``// Return false if number is not divisible by 2. ` `        ``if` `((str.charAt(n-``1``) -``'0'``)%``2` `!= ``0``) ` `           ``return` `false``; ` `      `  `        ``// If we reach here, number is divisible by 2. ` `        ``// Now check for 3. ` `      `  `        ``// Compute sum of digits ` `        ``int` `digitSum = ``0``; ` `        ``for` `(``int` `i=``0``; i

## Python3

 `# Python 3 program to find  ` `# if a number is divisible ` `# by 6 or not ` ` `  `# Function to find that number  ` `# is divisible by 6 or not ` `def` `check(st) : ` `    ``n ``=` `len``(st) ` `     `  `     `  `    ``# Return false if number ` `    ``# is not divisible by 2. ` `    ``if` `(((``int``)(st[n``-``1``])``%``2``) !``=` `0``) : ` `        ``return` `False` `  `  `    ``# If we reach here, number  ` `    ``# is divisible by 2. Now ` `    ``# check for 3. ` `  `  `    ``# Compute sum of digits ` `    ``digitSum ``=` `0` `    ``for` `i ``in` `range``(``0``, n) : ` `        ``digitSum ``=` `digitSum ``+` `(``int``)(st[i]) ` `  `  `    ``# Check if sum of digits ` `    ``# is divisible by 3 ` `    ``return` `(digitSum ``%` `3` `=``=` `0``) ` ` `  ` `  `# Driver code ` `st ``=` `"1332"` `if``(check(st)) : ` `    ``print``(``"Yes"``) ` `else` `: ` `    ``print``(``"No "``) ` `     `  `#  `

## C#

 `// C# program to find if a number is ` `// divisible by 6 or not ` `using` `System; ` ` `  `class` `GFG { ` `     `  `    ``// Function to find that number ` `    ``// divisible by 6 or not ` `    ``static` `bool` `check(String str) ` `    ``{ ` `        ``int` `n = str.Length; ` `     `  `        ``// Return false if number is ` `        ``// not divisible by 2. ` `        ``if` `((str[n-1] -``'0'``) % 2 != 0) ` `            ``return` `false``; ` `     `  `        ``// If we reach here, number is ` `        ``// divisible by 2. ` `        ``// Now check for 3. ` `     `  `        ``// Compute sum of digits ` `        ``int` `digitSum = 0; ` `        ``for` `(``int` `i = 0; i < n; i++) ` `            ``digitSum += (str[i] - ``'0'``); ` `     `  `        ``// Check if sum of digits is ` `        ``// divisible by 3 ` `        ``return` `(digitSum % 3 == 0); ` `    ``} ` `     `  `    ``// main function ` `    ``public` `static` `void` `Main ()  ` `    ``{ ` `        ``String str = ``"1332"``; ` `         `  `        ``if``(check(str)) ` `            ``Console.Write(``"Yes"``); ` `        ``else` `            ``Console.Write(``"No"``); ` `    ``} ` `} ` ` `  `// This code is contributed by parashar. `

## PHP

 ` `

## Javascript

 ` `

Output

`Yes`

Time Complexity: O(logN) where N is the given number
Auxiliary Space: O(1) since no extra space is being used

This article is contributed by DANISH_RAZA . If you like GeeksforGeeks and would like to contribute, you can also write an article using write.geeksforgeeks.org or mail your article to review-team@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

#### Approach#3: using the fact that it is divisible by 3 and 2 consecutive even numbers

We can check if a number is divisible by 6 by checking if it is divisible by 3 and any 2 consecutive even numbers (i.e., 2 and 4 or 4 and 6, etc.). We can use the modulo operation to find the remainder of the number when divided by 3 and check if it is divisible by any 2 consecutive even numbers.

#### Algorithm

1. Check if the remainder of the number when divided by 3 is 0.
2. Check if the last digit of the number is even.
3. If the last digit of the number is even, check if the second-last digit of the number is odd.
4. If the second-last digit of the number is odd, print “Yes”, otherwise print “No”.

## C++

 `// C++ program for the above approach ` `#include ` `using` `namespace` `std; ` ` `  `// Function to check divisibility by 6 ` `void` `check_divisibility_by_6(``int` `n) ` `{ ` `    ``if` `(n % 3 == 0 && n % 10 % 2 == 0 ` `        ``&& (n / 10) % 10 % 2 != 0) { ` `        ``cout << ``"Yes"` `<< endl; ` `    ``} ` `    ``else` `{ ` `        ``cout << ``"No"` `<< endl; ` `    ``} ` `} ` ` `  `// Driver Code ` `int` `main() ` `{ ` `    ``int` `n1 = 2112; ` `    ``check_divisibility_by_6(n1); ` ` `  `    ``int` `n2 = 1124; ` `    ``check_divisibility_by_6(n2); ` ` `  `    ``return` `0; ` `}`

## Java

 `public` `class` `Main { ` ` `  `    ``// Function to check divisibility by 6 ` `    ``public` `static` `void` `check_divisibility_by_6(``int` `n) { ` `        ``if` `(n % ``3` `== ``0` `&& n % ``10` `% ``2` `== ``0` `&& (n / ``10``) % ``10` `% ``2` `!= ``0``) { ` `            ``System.out.println(``"Yes"``); ` `        ``} ``else` `{ ` `            ``System.out.println(``"No"``); ` `        ``} ` `    ``} ` ` `  `    ``// Driver Code ` `    ``public` `static` `void` `main(String[] args) { ` `        ``int` `n1 = ``2112``; ` `        ``check_divisibility_by_6(n1); ` ` `  `        ``int` `n2 = ``1124``; ` `        ``check_divisibility_by_6(n2); ` `    ``} ` `} `

## Python3

 `def` `check_divisibility_by_6(n): ` `    ``if` `n ``%` `3` `=``=` `0` `and` `n ``%` `10` `%` `2` `=``=` `0` `and` `(n ``/``/` `10``) ``%` `10` `%` `2` `!``=` `0``: ` `        ``print``(``"Yes"``) ` `    ``else``: ` `        ``print``(``"No"``) ` ` `  ` `  `n ``=` `2112` `check_divisibility_by_6(n) ` ` `  `n ``=` `1124` `check_divisibility_by_6(n) `

## Javascript

 `function` `check_divisibility_by_6(n) { ` `  ``if` `(n % 3 === 0 && n % 10 % 2 === 0 && Math.floor(n / 10) % 10 % 2 !== 0) { ` `    ``console.log(``"Yes"``); ` `  ``} ``else` `{ ` `    ``console.log(``"No"``); ` `  ``} ` `} ` ` `  `let n = 2112; ` `check_divisibility_by_6(n); ` ` `  `n = 1124; ` `check_divisibility_by_6(n);`

## C#

 `using` `System; ` ` `  `class` `Program ` `{ ` `    ``// Function to check divisibility by 6 ` `    ``static` `void` `CheckDivisibilityBy6(``int` `n) ` `    ``{ ` `        ``if` `(n % 3 == 0 && n % 10 % 2 == 0 ` `            ``&& (n / 10) % 10 % 2 != 0) ` `        ``{ ` `            ``Console.WriteLine(``"Yes"``); ` `        ``} ` `        ``else` `        ``{ ` `            ``Console.WriteLine(``"No"``); ` `        ``} ` `    ``} ` ` `  `    ``// Driver Code ` `    ``static` `void` `Main(``string``[] args) ` `    ``{ ` `        ``int` `n1 = 2112; ` `        ``CheckDivisibilityBy6(n1); ` ` `  `        ``int` `n2 = 1124; ` `        ``CheckDivisibilityBy6(n2); ` ` `  `        ``Console.ReadKey(); ` `    ``} ` `} `

Output

```Yes
No```

Time Complexity: O(log n) where n is the value of the number.
Auxiliary Space: O(1).

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