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Python Loop Practice Problems
Write a Python program to calculate the factorial of a number using a loop.
7
7! = 5040
n = 7fact = 1for i in range(1, n + 1): fact *= iprint(f"{n}! = {fact}")7! = 5040
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Write a Python program to find all the factors of a number.
36
[1, 2, 3, 4, 6, 9, 12, 18, 36]
n = 36factors = []for d in range(1, n + 1): if n % d == 0: factors.append(d)print(factors)[1, 2, 3, 4, 6, 9, 12, 18, 36]
n % d == 0 means d is a factor.
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Write a Python program to calculate base raised to a power using a for loop.
base = 3, power = 4
3^4 = 81 | check: 81
power times.base, power = 3, 4result = 1for _ in range(power): result *= baseprint(f"{base}^{power} = {result}", "| check:", base ** power)3^4 = 81 | check: 81
The loop body runs exactly power times.
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Write a Python program that prints each digit of a number as a word.
1024
one zero two four
words = ["zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine"]n = 1024result = []for ch in str(n): result.append(words[int(ch)])print(" ".join(result))one zero two four
The list index is the digit, so words[4] is “four”.
Looping over str(n) gives the digits from left to right.
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Write a Python program to find how often each digit appears in an integer.
1223334441
1 -> 2 2 -> 2 3 -> 3 4 -> 3
n = 1223334441counts = {}while n > 0: d = n % 10 counts[d] = counts.get(d, 0) + 1 n //= 10for digit in sorted(counts): print(digit, "->", counts[digit])1 -> 2 2 -> 2 3 -> 3 4 -> 3
get(d, 0) returns 0 the first time a digit is seen.
Sorting the keys prints the digits in order.
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Write a Python program to check whether a number is a palindrome using a loop.
12321, 12345
12321 palindrome 12345 not a palindrome
for original in [12321, 12345]: n, rev = original, 0 while n > 0: rev = rev * 10 + n % 10 n //= 10 print(original, "palindrome" if rev == original else "not a palindrome")12321 palindrome 12345 not a palindrome
Work on a copy (n) so the original value is still available for the comparison.
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Write a Python program to read a number and print its reverse.
98760
6789
n = 98760reversed_n = 0while n > 0: reversed_n = reversed_n * 10 + n % 10 n //= 10print(reversed_n)6789
Shift the result left by one place and add the next digit.
The trailing 0 of 98760 becomes a leading zero, so the result prints as 6789.
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Write a Python program to calculate the product of the digits of a number.
4352
Product of digits: 120
n = 4352product = 1while n > 0: product *= n % 10 n //= 10print("Product of digits:", product)Product of digits: 120
The product starts at 1, because starting at 0 would make everything 0.
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Write a Python program to calculate the sum of the digits of a number.
40721
Sum of digits: 14
n = 40721total = 0while n > 0: total += n % 10 n //= 10print("Sum of digits:", total)Sum of digits: 14
n % 10 is the current last digit.
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Write a Python program to find the sum of the first and last digits of a number.
74351
7 + 1 = 8
n = 74351last = n % 10first = nwhile first >= 10: first //= 10print(first, "+", last, "=", first + last)7 + 1 = 8
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