What is Happy Number ?

If the input number is a single digit,

square it (multiply it by itself).

If the result or the original number has multiple digits, take each digit by itself and square the digit(multiply it by itself).

Repeat until you get to the number 1.

What is Sad Number ?

If the input number is a single digit,

square it (multiply it by itself).

If the result or the original number has multiple digits, take each digit by itself and square the digit (multiply it by itself).

Repeat until you get to the number 1.If number will never resolve to 1. Then, those numbers will never be happy.

In fact, the numbers will repeat this cycle forever. Thats sad.

Example for Happy Number

1 times itself (1 x 1) equals 1 and is, therefore, a happy number.

Example for Unhappy Number

2 times itself (2 x 2) equals 4.

4 squared (4 x 4) is 16 which, when split,

becomes (1 x 1) + (6 x 6) or 1 + 36 equals 37.

37 split up becomes (3 x 3) + (7 x 7)

(or)

9 + 49 equals 58. 58 split up and so on, finally the result number will never resolve to 1, therrefore, a unhappy or Sad number

List of First 100 Happy Numbers

1, 7, 10, 13, 19, 23, 28, 31, 32, 44, 49, 68, 70, 79, 82, 86, 91, 94, 97, 100, 103, 109, 129, 130, 133, 139, 167, 176, 188, 190, 192, 193, 203, 208, 219, 226, 230, 236, 239, 262, 263, 280, 291, 293, 301, 302, 310, 313, 319, 320, 326, 329, 331, 338, 356, 362, 365, 367, 368, 376, 379, 383, 386, 391, 392, 397, 404, 409, 440, 446, 464, 469, 478, 487, 490, 496, 536, 556, 563, 565, 566, 608, 617, 622, 623, 632, 635, 637, 638, 644, 649, 653, 655, 656, 665, 671, 673, 680, 683, 694, 700, 709, 716, 736, 739, 748, 761, 763, 784, 790, 793, 802, 806, 818, 820, 833, 836, 847, 860, 863, 874, 881, 888, 899, 901, 904, 907, 910, 912, 913, 921, 923, 931, 932, 937, 940, 946, 964, 970, 973, 989, 998, 1000