1: Yes.
2: Examine the last digit of N. If it is an even number, then N is divisible by 2.
3: Add the sum of the digits of N and call it P. If P is divisible by 3, than N is divisible by 3.
4: Take the last 2 digits of N and call it M. If M is divisible by 4, then N is divisible by 4.
5: Look at the last digit of N. If N is 5 or N is 0, then N is divisible by 5.
6: If N is divisible by 2 and N is divisible by 3, then N is divisible by 6.
7: Take the last digit of N and double it. Subtract this number from the rest of the digits in N. If that number is divisible by 7, N is divisible by 7.
8: Check the last 3 digits of N. if that is divisible by 8, N is divisible by 8.
9: Add the sum of the digits of N and call it Q. If Q is divisible by 9, than N is divisible by 9.
10: Look at the last digit of N. If N is 0, then N is divisible by 10.
11: Take the alternating sum of the digits in N, read from left to right. If that is divisible by 11, so is N.
12: If N is divisible by 3 and N is divisible by 4, then N is divisible by 12.
13: Multiply the digit at the unit place by 9 and find the difference between the product obtained and the rest of the number to its left. If the number is 0 or a multiple of 13, then we can say that N is divisible by 13.
14: If N is divisible by both 2 and 7 then N is divisible by 14.
15: If N is divisible by both 3 and 5 then N is divisible by 15.
16: Look at the last 4 digits of N. If that number is divisible by 16, N is divisible by 16.
17: Subtract five times the last digit from the remaining leading number. If the result is divisible by 17, then so was the first number. Apply this rule over and over again as necessary.
18: If N is divisible by 2 and N is divisible by 9, N is divisible by 18.
19: Add two times the last digit to the remaining leading truncated number. If the result is divisible by 19, then so is N. Apply this rule over and over again as necessary.
20: If N is divisible by 4 and if N is divisible by 5, N is divisible by 20.
