Python: Check if a number is positive, negative or zero

Last update on April 16 2025 13:04:44 (UTC/GMT +8 hours)

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Write a Python program to check if a number is positive, negative or zero.

Positive Numbers: Any number above zero is known as a positive number. Positive numbers are written without any sign or a '+' sign in front of them and they are counted up from zero, i.e. 1, + 2, 3, +4 etc.
Negative Numbers: Any number below zero is known as a negative number. Negative numbers are always written with a '−' sign in front of them and they are counted down from zero, i.e. -1, -2, -3, -4 etc.
Always look at the sign in front of a number to check if it is positive or negative. Zero, 0, is neither positive nor negative.

Pictorial Presentation:

Python: Check if a number is positive, negative or zero.

Sample Solution-1:

Python Code:

# Prompt the user to input a number, and convert the input to a floating-point number.
num = float(input("Input a number: "))

# Check if the number is greater than zero.
if num > 0:
   # If true, print that it is a positive number.
   print("It is a positive number")
# Check if the number is equal to zero.
elif num == 0:
   # If true, print that it is zero.
   print("It is zero")
else:
   # If the above conditions are not met, print that it is a negative number.
   print("It is a negative number")

Sample Output:

Input a number: 150                                                
It is positive number

Flowchart:

Sample Solution-2:

Python Code:

# Prompt the user to input a number and convert the input to a floating-point number.
n = float(input('Input a number: '))

# Use a conditional expression (ternary operator) to determine if the number is positive, zero, or negative.
# The conditional expression checks if the number is greater than 0, equal to 0, or less than 0.
# Depending on the condition met, it prints a corresponding message.
print('Number is Positive.' if n > 0 else 'It is Zero!' if n == 0 else 'Number is Negative.')

Sample Output:

Input a number:  0
It is Zero!

Sample Solution-3:

Python Code:

# Prompt the user to input a number and convert the input to a floating-point number.
n = float(input("Input a number: "))

# Check if the input number is greater than or equal to 0.
if n >= 0:
    # If the number is zero, print that it is zero.
    if n == 0:
        print("It is Zero!")
    # If the number is greater than zero, print that it is a positive number.
    else:
        print("Number is Positive number.")
# If the number is less than zero, print that it is a negative number.
else:
    print("Number is Negative number.")

Sample Output:

Input a number:  -150
Number is Negative number.

For more Practice: Solve these Related Problems:

Write a Python program to resolve a symbolic link to its real path.
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Write a Python program to normalize a given file path.
Write a Python program to check if a path exists before resolving it.

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