Descending Left-Growing Number Pattern in Python

What You’ll Learn

Program 8 prints a reverse left-growing number triangle: each row begins with the peak digit rows and grows by adding the next smaller digit to the right — 5, 54, 543, and so on. This tutorial covers the shape rule, descending outer loop, inner bound rows..i, a live preview, worked Python examples, edge cases, and complexity.

📝 Problem & Approach

Given row count rows = 5, print a reverse left-growing number triangle — inner loop prints digits rows..i on each row.

# rows = 5
#5
#54
#543
#5432
#54321

Inputs & Outputs

Minimal workflow

for i from rows down to 1:
    for j from rows down to i:
        print j
    print newline

Approach comparison

🔮 Live Preview

Choose a row count between 3 and 9 and draw the reverse left-growing number triangle in the browser.

Press "Draw pattern".

Examples Gallery

Three complete Python programs — fixed rows, user input, and a compact trace with rows = 3. Click View Output to reveal sample console results.

rows = 5

for i in range(rows, 0, -1):
    for j in range(rows, i - 1, -1):
        print(j, end="")
    print()

5
54
543
5432
54321

try:
    rows = int(input("Enter the number of rows: "))
    if rows <= 0:
        raise ValueError
except ValueError:
    print("Please enter a positive integer.")
else:
    for i in range(rows, 0, -1):
        for j in range(rows, i - 1, -1):
            print(j, end="")
        print()

Enter the number of rows: 4
4
43
432
4321

rows = 3

for i in range(rows, 0, -1):
    for j in range(rows, i - 1, -1):
        print(j, end="")
    print()

3
32
321

🔎 Worked Walkthrough — rows = 5

Trace each row — outer i is the inner stop, inner j runs from rows down to i.

Total digits printed: 1+2+3+4+5 = 15 = 5×6/2 — the fifth triangular number.

🎯 Practice Problems

Try these variations to lock in the pattern.

Notes

⏱️ Time and Space Complexity

💡 Best Practices