In this example, you will learn to check whether a number entered by the user is positive, negative or zero. This problem is solved using if...elif...else and nested if...else statement.

To understand this example, you should have the knowledge of following Python programming topics:

```
num = float(input("Enter a number: "))
if num > 0:
print("Positive number")
elif num == 0:
print("Zero")
else:
print("Negative number")
```

Here, we have used the `if...elif...else`

statement. We can do the same thing using nested `if`

statements as follows.

```
num = float(input("Enter a number: "))
if num >= 0:
if num == 0:
print("Zero")
else:
print("Positive number")
else:
print("Negative number")
```

The output of both programs will be the same.

**Output 1**

Enter a number: 2 Positive number

**Output 2**

Enter a number: 0 Zero

A number is positive if it is greater than zero. We check this in the expression of `if`

. If it is `False`

, the number will either be zero or negative. This is also tested in subsequent expression.