# How do you prove a number is divisible by 9 if the sum of its digits is divisible by 9?

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## How do you prove a number is divisible by 9 if the sum of its digits is divisible by 9?

A number expressed in decimal notation is divisible by 9 if and only if the sum of its digits is divisible by 9. That is: N=[a0a1a2…an]10=a0+a110+a2102+⋯+an10n is divisible by 9.

### What is the divisibility rule for numbers divisible by 9?

A number is divisible by 9, if the sum is a multiple of 9 or if the sum of its digits is divisible by 9. Consider the following numbers which are divisible by 9, using the test of divisibility by 9: 99, 198, 171, 9990, 3411. Sum of the digits of 99 = 9 + 9 = 18, which is divisible by 9.

**Which of the following numbers is divisible by 9 *?**

Consider the following numbers which are divisible by 9, using the test of divisibility by 9: 99, 198, 171, 9990, 3411. Sum of the digits of 99 = 9 + 9 = 18, which is divisible by 9.

**What is the divisibility of 8?**

Divisibility rules for numbers 1–30

Divisor | Divisibility condition | Examples |
---|---|---|

8 | If the hundreds digit is even, the number formed by the last two digits must be divisible by 8. | 624: 24. |

If the hundreds digit is odd, the number obtained by the last two digits plus 4 must be divisible by 8. | 352: 52 + 4 = 56. |

## What is the divisibility Rule 12?

Divisibility guidelines for 12: In order to know if a number is divisible by 12, you have to first check if it is divisible by 3 and 4. If it is divisible by both 3 and 4, then the number is divisible by 12.

### Which of the number is not divisible by 9?

Consider the following numbers which are not divisible by 9, using the rules of divisibility by 9: 73, 237, 394, 1277, 1379. Sum of the digits of 73 = 7 + 3 = 10, which is not divisible by 9.

**How many factors does 54 have?**

The Pair Factors of 54 are (1, 54), (2, 27), (3, 18), and (6, 9) and its Prime Factors are 1, 2, 3, 6, 9, 18, 27, 54….Factors of 54 in Pairs.

Factors | Pair factors |
---|---|

54 × 1 = 54 | 54, 1 |