Programming Questions on loops

Problems on loops are one of the most often asked questions during Software Interviews and also exams.

Please attempt these problems and then look up the answers..

• Write a program to  print all the Prime Numbers from 2 to 500. Your program should count the number of primes as well.

• Write a program to print all the Pythagorean Triplets between 1 to 100. Combinations like 3² + 4² = 5²

• Write a program to check for palindromes among strings

• Write a program to print all permutations of a given number
• Write a program to find all prime factors of a number.
• Write a program to print the hexadecimal of a decimal number.
• Check for a Happy Number. A Happy is one whose sum of squares of digits ultimately reaches one.
  Eg
  19 = 1² + 9² = 1 + 81 = 82 = 8² + 2² = 64 + 4= 68 =  6² + 8² = 36 + 64 = 1² + 0² + 0² = 1 + 0 + 0=1
• Perfect number is a number that is equal to the sum of its proper divisors. 6 = 1 + 2 + 3.
• Armstrong number is equal to the sum of cubes of its digits.
  Eg 371= 3³ + 7³ + 1³ = 27 + 343 + 1= 371.
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