Python Program to Determine Whether a Given Number is Even or Odd Recursively

Last Updated : 20 May, 2021

In this article, We will see how to write the program to find the given number is Even or Odd Using the Recursion Method. If the number is even returned true else false in Python.

For that, we use the Operator Called Modulus Operator. This operator used in the operation when we need to calculate the remainder of that number when divided by any divisor.

Even Number: A number Which is completely divisible by 2 Hence remainders is 0
Odd Number: A number which is not divisible by 2 Hence remainders is 1

Examples:

Input: 2
Output: True
Explanation : 2 % 2==0 So True

Input: 5
Output: False 
Expalantion : 2 % 2 != 0 So, False

Methods #1:

Approach :

We use the concept of getting the remainder without using the modulus operator by subtracting the number by number-2
If at last, we get any remainder then that number is odd and return the False for that number
Else the number is even and return True for that number

Python3

# defining the function having the one parameter as input
def evenOdd(n):
     
    #if remainder is 0 then num is even
    if(n==0):
        return True
       
    #if remainder is 1 then num is odd
    elif(n==1):
        return False
    else:
        return evenOdd(n-2)
       
# Input by geeks
num=3
if(evenOdd(num)):
    print(num,"num is even")
else:
    print(num,"num is odd")

Output:

3 num is odd

Methods #2:

We use the modulus operator to find the even or odd Like if num % 2 == 0 then the remainder is 0 so the given number is even and return True

Else if num % 2 != 0 then the remainder is not zero so the given number is odd and return False

Python3

# defining the function having
# the one parameter as input
def evenOdd(n):
     
    #if remainder is 0 then num is even
    if(n % 2 == 0):
        return True
     
    #if remainder is 1 then num is odd
    elif(n %2 != 0):
        return False
    else:
        return evenOdd(n)
 
# Input by geeks
num = 3
if(evenOdd( num )):
    print(num ,"num is even")
else:
    print(num ,"num is odd")

Output:

3 num is odd

Methods #3: To print all the even number for the range (a, b)

Here We will print all the even number for the Given Range n in the Function evenOdd(n)

Python3

# writing the function having the range
# and printing the even in that range
def evenOdd(a,b):
    if(a>b):
        return
    print(a ,end=" ")
    return evenOdd(a+2,b)
 
# input by geeks
x=2
y=10
if(x % 2 ==0):
    x=x
     
else:
     
    # if the number x is odd then
    # add 1 the number into it to
    # avoid any error to make it even
    x+=1
evenOdd(x,y)

Output:

2 4 6 8 10

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