(2) If the sum of the numbers of an integer is divisible by 3, then the integer can be divisible by 3.

(3) If the last two digits of an integer are divisible by 4, then this number can be divisible by 4.

(4) If the last digit of an integer is 0 or 5, then this number can be divisible by 5.

(5) If an integer is divisible by 2 and 3, then this number is divisible by 6.

(6) If the single digit of an integer is truncated, then 2 times of the single digit is subtracted from the remainder. If the difference is a multiple of 7, the original number can be divisible by 7. If the difference is too large or it is difficult to see whether it is a multiple of 7 in mental arithmetic, you need to continue the above-mentioned process of "rounding, multiplication, subtraction and difference test" until you can clearly judge. For example, the process of judging whether 133 is a multiple of 7 is as follows: 13-3× 2 = 7, so 133 is a multiple of 7; For another example, the process of judging whether 6 139 is a multiple of 7 is as follows: 6 13-9× 2 = 595, 59-5× 2 = 49, so 6 139 is a multiple of 7, and so on.

(7) If the last three digits of an integer are divisible by 8, then this number can be divisible by 8.

(8) If the sum of the numbers of an integer is divisible by 9, then the integer can be divisible by 9.