A number is divisible by three if
Its digits add up to a multiple of 3
A number is divisible by 4 if
Its last two digits are divisible by 4
A number is divisible by 5
If last digit is a 5 or 0
A number is divisible by 6
Apply the rules of 2 and 3
A number is divisible by 9 if
Its digits add up to a multiple of 9 (235,692 ; 2+3+5+6+9+2 = 27)
A number is divisible by 12 if
Apply the rules of 3 and 4