What is Divisible?
In Mathematics, a number is said to be divisible by another number is said to be divisible if it does not produce a remainder. That means when you divide the two numbers, the remainder should be a 0. You can tell if a number is divisible by something by checking whether it meets the divisibility rules. These are set of rules that help people know whether a number is divisible by another number without carrying out the division.
Divisibility Rules 1- 20
1. Any number is divisible by 1. Because when you divide any number by 1, you will always get the number itself.
For example 64 ¸ 1 = 64
2. A number is divisible by 2 if it’s an even number or ends with 0, 2, 4, 6, and 8.
For example 248 ¸ 2 = 124
3. A number is divisible by 3 if the total sum of its digits is divisible by 3
For Example 282 is divisible by 3 because 2 + 8 + 2 = 12.
282 ¸ 3 = 94
4. A number is divisible by 4 if its last two digits are divisible by 4
For Example, 964 is divisible by 4 because 64 is divisible by 4
964 ¸ 4 = 241
5. A number is divisible by 5 if the last digit ends with a Zero or a 5
For example, 1085 is divisible by 5 because the last digit is a 5
1085 ¸ 5 = 217
6. A number is divisible by 6 if it’s divisible by both numbers 2 and 3
For example, 90 is divisible by 6 since it’s divisible by 2 and 3
90 ¸ 2 = 45
90 ¸ 3 = 30
90 ¸ 6 = 15
7. A number is divisible by 7 if the difference between twice its unit digits from the remaining part is a 0 or a multiple of 7
For example, 574 is divisible by 7 because 57- 8 =49 (49 is a multiple of 7)
8. A number is divisible by 8 if the last 3 digits are divisible by 8
For example: 600, 256 is divisible by 8 because 256 is divisible by 8. But 90, 413 is not divisible by 8 because 513 is not divisible by 8.
9. A number is divisible by 9 if the sum of its digits is divisible by 9
For example, 909 is divisible by 9 because 9 +0 +9 =18 (18 is divisible by 9)
10. A number is divisible by 10 if its last digit is a 0
For Example, 10, 20, 30, 40, 50, 60, 70
11. A number is divisible by 11 if the difference of its sums of alternating digits from left to the right is divisible by 11 or it’s a 0
For example 2849 is divisible by 11 because: 2+4 = 6, 8+9=17 >> 17-6= 11
12. A number is divisible by 12 if it can be divided by both 3 and 4
For example 36 is divisible by 12 because 36 ¸ 4 = 9 and 36 ¸ 3 = 12
13. A number is divisible by 13 if the number at the one’s position can be multiplied by 4 and then added to the rest to produce a multiple of 13 or a 0
For example, 3367 is divisible by 13 because;
7 × 4= 28
336 +28 = 364
364 is a multiple of 13 (13 × 28 =364)
14. A number is divisible by 14 if it can be divided by both 7 and 2
For example, 84 is divisible by 7 because
84 ¸ 7 = 12
84 ¸2 = 42
15. A number is divisible by 15 if it’s divisible by both 3 and 5
For example, 90 is divisible by 15 because
90 ¸ 5 = 18
90 ¸ 3 = 30
16. A number is divisible by 16; if the last two digits are added four times, the remaining numbers result in a number divisible by 16.
For example 1168 is divisible by 16 because
68 + (11 × 4) = 112 (112 is divisible by 16)
17. A number is divisible by 17 if subtract the last two digits from two times the rest and produces a number divisible by 17
For example 4675 is divisible by 17 because:
46 × 2 – 75 = 17
18. A number is divisible by 18 if it can be divided by both 2 and 9
For example, 180 is divisible by 18 because
180 ¸ 2 = 90
180 ¸ 9 =20
19. A number is divisible by 19 if you add 4 times the last two digits to the remaining, and the answer is divisible by 19
For example 6935 is divisible by 19 because 69 +35 × 4 =209.
20. A number is divisible by 20 if it’s divisible by 4 and 5 or if the last two digits form a number that is divisible by 20
For example, 220 is divisible by 20 because
220 ¸ 5 = 44
220 ¸ 4 = 55