Python Repeating Number Triangle Pattern (Inverted)
Beginner
5 min read
Updated: Sep 2026
3 programs
Live preview
Definition
What Is This Pattern?
An inverted repeating number triangle prints digit i repeated exactly i times, counting i down from rows.
Remember
Rule: for i = n..1, print i exactly i times
55555
4444
333
22
1 ← 5 rows
In Python you solve it with two nested for loops: the outer loop picks the digit, the inner loop repeats it with print(i, end=""), then bare print() ends the row. Program 9 is the ascending twin (1, 22, 333…); Program 10 grows repeats while the digit falls (5, 44, 333…).
Approach
How to Solve It
Outer loop counts down from rows to 1. Inner loop repeats digit i exactly i times. End each row with print().
Method
Idea
Best for
Nested loops
Outer picks digit n..1; inner repeats it i times
Learning, interviews, exams
str(i) * i
Build each full row in one call
Leaner demos once loops click
Pseudocode
Pseudocode
for i from rows down to 1:
for j from 1 to i:
print i (no newline)
print newline
Cheat sheet
Goal
Pattern
Pick digit (count down)
for i in range(rows, 0, -1):
Repeat digit i
for j in range(1, i + 1): print(i, end="")
End the row
print()
String multiply form
print(str(i) * i)
Program 10 twin
for j in range(rows, i - 1, -1): print(i, end="") (grows repeats)
Printing Numbers vs Starting a New Line
API
Effect
Use for
print(i, end="")
Stays on the same line
Each repeat of digit i
print()
Ends the current line
After the inner loop
Print all repeats without a newline, then end the row once.
Try it
Live Preview
Change the row count and the inverted triangle updates instantly — capped at 9 so every digit stays a single character.
Whole numbers from 1 to 9 (single digits). Tap a chip or type a value — the preview redraws as you go.
Live result5 rows · 15 digits
55555
4444
333
22
1
Trace
Worked Walkthrough
Trace rows = 4 — each outer-loop value of i, how many times the inner loop runs, and the printed row.
i
Inner j
Repeats
Printed row
4
1..4
4
4444
3
1..3
3
333
2
1..2
2
22
1
1..1
1
1
Total digits are 4+3+2+1 = 10 — the triangular number n(n+1)/2.
Code
Python Programs
Three complete programs: fixed height, input(), and a string-multiply shortcut. Use View Output for sample results.
Example 1 — Fixed rows = 5
Outer loop picks the digit; inner loop repeats it exactly i times.
Python
rows = 5
for i in range(rows, 0, -1):
for j in range(1, i + 1):
print(i, end="")
print()
Output
55555
4444
333
22
1
How It Works
1. Count down.for i in range(rows, 0, -1) yields 5, 4, 3, 2, 1 — the digit for each row.
2. Match repeats to digit. When i = 5, the inner loop runs five times (55555); when i = 1, it runs once (1).
3. Newline. Bare print() after the inner loop starts the next shorter row of a smaller digit.
Example 2 — User Input
Read the row count from the keyboard. Prefer a try / except in real apps (shown in the tip below).
Python
rows = int(input("Enter the number of rows: "))
for i in range(rows, 0, -1):
for j in range(1, i + 1):
print(i, end="")
print()
Output (when user enters 4)
Enter the number of rows: 4
4444
333
22
1
How It Works
1. Read rows.input() returns a string; int(...) converts it to a whole number.
2. Same nested loops. Four rows start at 4444 and end at 1.
3. Safer input tip. Bare int(input()) raises ValueError on letters. Prefer:
Safer input
raw = input("Enter the number of rows: ").strip()
try:
rows = int(raw)
except ValueError:
print("Enter a positive whole number.")
raise SystemExit(1)
if rows < 1:
print("Enter a positive whole number.")
raise SystemExit(1)
Example 3 — String Multiply Shortcut
Same shape with one call per row — best once the “digit equals count” rule is clear.
Python
rows = 5
for i in range(rows, 0, -1):
print(str(i) * i)
Output
55555
4444
333
22
1
How It Works
1. Count still equals digit.str(i) * i builds the same row the inner loop printed.
2. Same shape. Identical output to Example 1 — keep the nested-loop version for exams that expect two loops.
3. Convert first.str(i) * i needs a string — multiplying an int would raise an error.
Edge Cases & Pitfalls
Check these before calling the solution done.
wrong twin
for j in range(rows, i - 1, -1)
That is Program 10 (5, 44, 333). Here digit and count both equal i.
print() inside
Bare print(i) inside the inner loop
That puts each digit on its own line. Use print(i, end="") for repeats; call bare print() only after the row finishes.
count up
for i in range(1, rows + 1) with print(i) × i
That is Program 9 (1, 22, 333). Keep counting down so the widest row comes first.
rows = 1
Single digit
Output is just 1 — a good sanity check.
rows ≤ 0
Empty output
The outer loop never runs. Validate and prompt again for clearer UX.
multi-digit
rows > 9
print(10, end="") prints two characters. Labs usually stick to 1–9 for a clean single-digit look.
Analysis
Time and Space Complexity
Program
Time
Extra space
Nested loops (Examples 1–2)
O(n²)
O(1)
String multiply (Example 3)
O(n²)
O(1) beyond the row string
There are n rows printing n+(n-1)+…+1 digits, so total work is n(n+1)/2.
Remember
Key Takeaways
Rule: for i = n..1, print digit i exactly i times.
Inner bound:range(1, i + 1) so digit and count stay equal.
end= vs print(): repeats stay on the line; bare print() advances after each row.
Next step: Program 12 shrinks while counting up (11111, 2222, 333…).
One line: for each digit from n down to 1, print it i times with end="", then call print().
Frequently Asked Questions
The outer loop decreases i from rows down to 1, and the inner loop runs j from 1 to i. Row i repeats digit i exactly i times, so the widest row is first and each next row is shorter.
for j in range(1, i + 1): print(i, end="") runs the inner body i times. When i is 5 you get 55555; when i is 1 you get a single 1.
print(i, end="") stays on the same line. print() ends the current line. Repeated digits use end=""; the row break uses print() after the inner loop.
Program 10 grows repeat count as the digit shrinks (5, 44, 333, 2222, 11111) using for j in range(rows, i - 1, -1). Program 11 repeats digit i exactly i times (55555, 4444, 333, 22, 1) using for j in range(1, i + 1).
O(n²) where n is the number of rows. Total print calls equal n+(n-1)+…+1 = n(n+1)/2.
Yes. print(str(i) * i) prints a full row in one call. Nested loops are better for learning; str(i) * i is a handy shortcut once the bounds make sense.
Wrap int(input()) in try/except ValueError, or check that the raw string is digits, and require rows >= 1.
The outer loop never runs, so nothing is printed. Validate and prompt again if you want a clear user message.
🤔
Did you know?
Row digit i repeats exactly i times. The outer loop counts down from rows, so the first row is widest (rows copies of rows) and each line shortens — still O(n²) total prints.
