The number is divisible by:
- 2 if the last digit is 0, 2, 4, 6, or 8 Example: 12346
- 3 if the sum of digits in the number are divisible by 3 Example: 1236, because 1+2+3+6 = 12 = 3 x 4
- 4 if the last 2 digits are divisible by 4 Example: 897544, because 44 = 4 x 11
- 5 if the last digit is 0 or 5 Example: 178965 or 40980
- 6 if it is divisible by 2 and 3;
- 7 sorry, no rule
- 8 if the last 3 digits are divisible by 8 Example: 124987080, because 080 = 8 x 10;
- 9 if the sum of digits is divisible by 9 Example: 234612, because 2+3+4+6+1+2 = 18 = 9 x 2
- 10 if the last digit is 0 Example: 99990
- 100 if the last 2 digits are 0 Example 987600
NOTE: If a number is divisible by 2 factors, it is also divisible by the product of these factors.
Example 1: Number 18 is divisible by 2 and 3, so it must be divisible by 2 x 3 = 6.
Example 2: Number 945 is divisible by 9 (why?) and by 5 (why?), so it must be divisible by 9 x 5 = 45. (Can you check it?)