Check whether tens ( or second last ) digit is odd or even If n = 375 , So n / 10 = 37 and ( n / 10 ) % 10 = 7 Applying formula for even and odd cases .
if ( ( ( n / 10 ) % 10 ) % 2 == 0 ) return ( 6 * lastNon0Digit ( n / 5 ) * dig [ n % 10 ] ) % 10 ; else return ( 4 * lastNon0Digit ( n / 5 ) * dig [ n % 10 ] ) % 10 ; }