Table of 5 with a for loop

Write a Python program to print the multiplication table of 5 with a for loop.

5 x 1 = 5
5 x 2 = 10
5 x 3 = 15
5 x 4 = 20
5 x 5 = 25
5 x 6 = 30
5 x 7 = 35
5 x 8 = 40
5 x 9 = 45
5 x 10 = 50

Approach

1. Loop i from 1 to 10.

Solution

for i in range(1, 11):    print(f"5 x {i} = {5 * i}")

5 x 1 = 5
5 x 2 = 10
5 x 3 = 15
5 x 4 = 20
5 x 5 = 25
5 x 6 = 30
5 x 7 = 35
5 x 8 = 40
5 x 9 = 45
5 x 10 = 50

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Star triangle up and down

Write a Python program to print stars growing from 1 to 5 and back to 1.

* 
* * 
* * * 
* * * * 
* * * * * 
* * * * 
* * * 
* * 
* 

Approach

1. Build the list of row sizes 1..5..1 and print each.

Solution

n = 5sizes = list(range(1, n + 1)) + list(range(n - 1, 0, -1))for s in sizes:    print("* " * s)

* 
* * 
* * * 
* * * * 
* * * * * 
* * * * 
* * * 
* * 
* 

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Does a string contain a digit?

Write a Python program to check whether a string contains a digit.

"Python123", "Python"

Python123 True
Python False

Approach

1. Loop until a digit is found; use for ... else for the “not found” case.

Solution

for text in ["Python123", "Python"]:    for ch in text:        if ch.isdigit():            print(text, True)            break    else:        print(text, False)

Python123 True
Python False

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Validate a password

Write a Python program to check a password: at least one lowercase letter, one uppercase letter, one digit, one of $ # @, and 5 to 15 characters long.

"Abc@1234", "abc123", "Ab1$"

Abc@1234 -> Valid password
abc123 -> Invalid: needs an uppercase letter, needs one of $#@
Ab1$ -> Invalid: length must be 5-15

Approach

1. Loop over the characters once, recording which kinds were seen.
2. Check all rules at the end and list any that failed.

Solution

def check(password):    has_lower = has_upper = has_digit = has_special = False    for ch in password:        if ch.islower():            has_lower = True        elif ch.isupper():            has_upper = True        elif ch.isdigit():            has_digit = True        elif ch in "$#@":            has_special = True    problems = []    if not 5 <= len(password) <= 15:        problems.append("length must be 5-15")    if not has_lower:        problems.append("needs a lowercase letter")    if not has_upper:        problems.append("needs an uppercase letter")    if not has_digit:        problems.append("needs a digit")    if not has_special:        problems.append("needs one of $#@")    return "Valid password" if not problems else "Invalid: " + ", ".join(problems) for pw in ["Abc@1234", "abc123", "Ab1$"]:    print(pw, "->", check(pw))

Abc@1234 -> Valid password
abc123 -> Invalid: needs an uppercase letter, needs one of $#@
Ab1$ -> Invalid: length must be 5-15

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Fibonacci numbers up to 55

Write a Python program to print the first 11 Fibonacci numbers (0 to 55).

0 1 1 2 3 5 8 13 21 34 55

Approach

1. Build a list starting [0, 1] and append the sum of the last two.

Solution

fib = [0, 1]while len(fib) < 11:    fib.append(fib[-1] + fib[-2])print(*fib)

0 1 1 2 3 5 8 13 21 34 55

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Number triangle 1, 22, 333

Write a Python program to print row i with the number i repeated i times, for i from 1 to 5, using nested loops.

1 
2 2 
3 3 3 
4 4 4 4 
5 5 5 5 5 

Approach

1. An inner loop prints the row number i times.

Solution

for i in range(1, 6):    for _ in range(i):        print(i, end=" ")    print()

1 
2 2 
3 3 3 
4 4 4 4 
5 5 5 5 5 

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Inverted right triangle of stars

Write a Python program to print an inverted right triangle of stars with 5 rows.

* * * * * 
* * * * 
* * * 
* * 
* 

Approach

1. Count rows down from 5 to 1.

Solution

for i in range(5, 0, -1):    print("* " * i)

* * * * * 
* * * * 
* * * 
* * 
* 

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Right triangle of stars

Write a Python program to print a right triangle of stars with 5 rows.

* 
* * 
* * * 
* * * * 
* * * * * 

Approach

1. Row i prints i stars.

Solution

for i in range(1, 6):    print("* " * i)

* 
* * 
* * * 
* * * * 
* * * * * 

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Numbers from 0 to 100 divisible by 5

Write a Python program to find the numbers from 0 to 100 divisible by 5.

[0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100]

Approach

1. Keep numbers with n % 5 == 0.

Solution

print([n for n in range(0, 101) if n % 5 == 0])

[0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100]

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Sum of odd numbers 1 to 100

Write a Python program to calculate the sum of all odd numbers from 1 to 100.

2500

Approach

1. Loop over odd numbers and add them.

Solution

total = 0for n in range(1, 101, 2):    total += nprint(total)

2500

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