Find the unit place digit of sum of N factorials | Function to find the unit 's place digit ; Let us write for cases when N is smaller than or equal to 4. ; We know following ( 1 ! + 2 ! + 3 ! + 4 ! ) % 10 = 3 else ( N >= 4 ) ; Driver code
function get_unit_digit ( N ) { if ( N == 0 N == 1 ) return 1 ; else if ( N == 2 ) return 3 ; else if ( N == 3 ) return 9 ; return 3 ; } var N = 1 ; for ( N = 0 ; N <= 10 ; N ++ ) document . write ( " " + N + " " + get_unit_digit ( N ) + " " )