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How to Print Number Sequences (1-10 and 10-1) in Python Loops

Generating and printing sequences of numbers, like 1 to 10 or 10 down to 1, is a fundamental programming task.

This guide demonstrates how to achieve this using for loops with range() and reversed(), as well as while loops, providing clear examples for both ascending and descending sequences.

Printing 1 to 10 (Ascending)​

The range() function combined with a for loop is the most common and Pythonic way to print numbers 1 through 10:

for num in range(1, 11): # Stop value is 11 (exclusive)
    print(num)

Output:

1
2
3
4
5
6
7
8
9
10
  • range(1, 11) generates numbers starting from 1 up to (but not including) 11.
  • To exclude 10, use range(1, 10).

Using a while Loop​

You can achieve the same result with a while loop, but it's generally more verbose:

number = 1
while number <= 10:
    print(number)
    number += 1 # Crucial: Increment the counter

Output:

1
2
3
4
5
6
7
8
9
10
  • The loop continues as long as number is less than or equal to 10.
  • You need to manually increment the number in each iteration.

Printing 10 to 1 (Descending)​

The cleanest way to print in reverse order is to use range() to generate the forward sequence and then reverse it with reversed():

for num in reversed(range(1, 11)):
    print(num)

Output:

10
9
8
7
6
5
4
3
2
1
  • range(1, 11) creates the sequence 1, 2, ..., 10.
  • reversed(...) returns a reverse iterator for that sequence.

Using a for Loop with range() (Alternative)​

You can also use range() directly with a negative step:

for num in range(10, 0, -1): # Start=10, Stop=0 (exclusive), Step=-1
    print(num)

Output:

10
9
8
7
6
5
4
3
2
1
  • The arguments to the range() function are start (inclusive), stop (exclusive) and step.
  • The step of -1 means that the numbers will be generated in reverse order.

Using a while Loop​

A while loop can also print numbers in descending order:

number = 10
while number >= 1:
    print(number)
    number -= 1 # Crucial: Decrement the counter

Output:

10
9
8
7
6
5
4
3
2
1
  • The loop continues as long as number is greater than or equal to 1.
  • You manually decrement number in each iteration.

Conclusion​

This guide demonstrated how to print sequences of numbers from 1 to 10 and 10 to 1 in Python.

For both ascending and descending sequences, using a for loop with range() (and reversed() for descending) is generally the most recommended, concise, and Pythonic approach. While while loops offer flexibility, they require manual counter management and are often more verbose for simple sequential tasks.

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