Function to calculate the sum of numbers divisible by 3 or 4
function sum ( N ) { var S1 , S2 , S3 ; S1 = ( ( N / 3 ) ) * ( 2 * 3 + ( N / 3 - 1 ) * 3 ) / 2 ; S2 = ( ( N / 4 ) ) * ( 2 * 4 + ( N / 4 - 1 ) * 4 ) / 2 ; S3 = ( ( N / 12 ) ) * ( 2 * 12 + ( N / 12 - 1 ) * 12 ) / 2 ; return S1 + S2 - S3 ; }