Add remaining digits of larger number
for ( let i = n1 ; i < n2 ; i ++ ) { let sum = ( ( str2 [ i ] . charCodeAt ( 0 ) - ' ' . charCodeAt ( 0 ) ) + carry ) ; str += String . fromCharCode ( sum % 10 + ' ' . charCodeAt ( 0 ) ) ; carry = Math . floor ( sum / 10 ) ; }