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This is a program to find out if any number from 1 to 999 is a happy number. Before I put the code in though, some of you may be wondering what a happy number is though. To find a happy number: Take X (Ex. 123) Take each of the digits in X and square them (Ex. 1²,2²,3²) Add the squares (Ex. 1+4+9=14) Keep on doing this until you get either 1 or 4. If you get 1, the number is happy; if you get 4, it is not. Here is the code. It might not be in the most convenient format, but here it is:

Lbl A
Prompt J
Goto B
Lbl B
If J>999:Goto A
If 1000>J>99:Goto C
If 100>J>9:Goto D
If 10>J>0 Goto E

Here's where things get complicated. I'll try to explain in words what the code is. The explanation is after the // on each line, so don't put it in the actual program.

Lbl C
(J/100)→K //To isolate each digit, I first divided the number by 100 (Ex. 123 becomes 1.23)
iPart(K)→T //Then, I took the integer part, which was formerly the hundreds digit. (Ex. 1.23 becomes 1)
(K-T)→O // Next, I subtracted the iPart from the full number, so that I had only 2 digits. (Ex. 1.23-1 becomes 0.23)
(O*10)→L //And then I multiplied the new number by 10 to get the next digit. (Ex. 0.23 becomes 2.3)
iPart(L)→U //(Ex. 2.3 becomes 2)
(L-U)→P //(Ex. 2.3-2 becomes 0.3)
(P*10)→V //(Ex. 0.3 becomes 3)
Goto B //At the end, we plug the final number back into J and check for the number of digits.

The next piece of code (if J has 2 digits) works the same way.

Lbl D
Goto B

The last part (if J has only 1 digit) is a bit different.

Lbl E
If J=1 or 4
Goto F
J²→J:Goto B
Lbl F
If J=1:Disp "HAPPY"
If J=4:Disp "NOT HAPPY"

Again, I know it isn't the most effective method, but it was the first one I came up with. Perhaps, when I am better at coding, I will find a more effective way to do this, but for now, here it is.

Have fun trying out numbers!