# prime numbers having 3 digits and starting with 5
for primeNumbers in range(100, 999 + 1):
    if primeNumbers // 100 == 5: 
        for divider in range(2, primeNumbers):
            if (primeNumbers % divider) == 0:
                break
        else:
            print(primeNumbers)
            

Begin
    start numbers counting between 100 and 999
    check the number if starting with 5
    repeat counting numbers until primeNumbers
        if primeNumbers can be divided by divider, break
        other situation print the primeNumbers
end