Python Classroom notes 02/Sep/2026

Problems

Prime number

• Solution

number = 7
start = 2
is_prime = True
until start < number
    if number % start == 0
        is_prime = False
        exit or break
    start = start + 1
say is_prime

• optimization

number = 7
start = 2
is_prime = True
until start <= number / 2
    if number % start == 0
        is_prime = False
        exit or break
    start = start + 1
say is_prime

Reverse Number

• Example

157 => 751
737 => 737

• solution

number = 731
orig = number
rev = 0
until number > 0
   rev = number % 10 + rev * 10
   number = number / 10
say rev
if rev == orig
   say "pallendrome"

Exercise

• Find the largest factor of a number

100
   => 50

• Find the largest prime factor of a number

100
  => 5

33
  => 11