2378 if 0 in the last then it must be in pairs or even. if the unit no. is 5 then the tens place must be 2. if the unit is 6 then the tens place must be odd. if the unit is 9,1,4, then the tens place must be even. when you have the last digit is even ,then the divisibility test of 8 if it gives you remainder 0 and 4,then when you have the last digit is odd ,then the divisibility test of 8 if it gives you remainder 1,then digital root check 1,4,7,9