var a=1234; sum=0; while (a){ sum+=a%10; a=(a-a%10)/10; } alert (sum); //output:10 how this can output 10? Any explanation?

Question

Javasicrip

Answer 1

Here, loop will run until a become 0(false).
And every time sum+=a%10 statement add last digit to sum.
So in first loop sum+=4, second sum+=3, third sum+=2, fourth sum+=1 and now sum is 10.
The second statement is used to remove digit which is the once added from a.

Answer 2

Raj Chhatrala thank you very much