Find the value of b mod 11 for large value of a as per the derived formula
for ( let i = b . length - 1 ; i >= 0 ; i -- ) { b_mod_11 = ( b_mod_11 + w * ( b [ i ] . charCodeAt ( 0 ) - ' ' . charCodeAt ( 0 ) ) ) % 11 ; w = w * - 1 ; }