Divisibility - 11

Category: Arithmetic

"Published in Vacaville, California, USA"

Divisibility by 11:

How do you know that a number is divisible by 11? Well, a number is divisible by 11 if the difference of the two groups is a multiple of 11. Each group is the sum of the alternate digits of a given number. 

Example 1:

The first thing that we need to do is to inspect the given number if it is divisible by 11 or not.

The first group of alternating digits is 2, 7, and 6 and the second group of alternating digits is 0 and 3.

Hence, the difference of the two group is

 

Since the difference of the two groups is not a multiple of 11, then the given number is not divisible by 11. There's a remainder of 1 in the division. The answer or a quotient must be a whole number itself. You should not have a fraction or a remainder in the final answer. 

Example 2:

The first thing that we need to do is to inspect the given number if it is divisible by 11 or not.

The first group of alternating digits is 8, 5, and 7 and the second group of alternating digits is 0, 3, and 6.

Hence, the difference of the two group is

Since the difference of the two groups is a multiple of 11, then the given number is divisible by 11. There's no remainder or a fraction in the division.

You should consider in studying the divisibility of a number because you will use these principles later when you will study higher Math subjects that involves the division of a number, simplifying fractions, and even factoring. 

This method can also be used for negative integers as long as the difference of the two groups of the sum of alternating digits of a given number is a multiple of 11. Again, there should be no remainder or a fraction in the division.      

Divisibility - 10

Category: Arithmetic

"Published in Newark, California, USA"

Divisibility by 10:

How do you know that a number is divisible by 10? Well, a number is divisible by 10 if the last digit of a given number is 0. 

Example 1:

The first thing that we need to do is to inspect the given number if it is divisible by 10 or not.

Since the last digit of a given number is not 0, then the given number is not divisible by 10. There's a remainder of 5 in the division. The answer or a quotient must be a whole number itself. You should not have a fraction or a remainder in the final answer. 

Example 2:

The first thing that we need to do is to inspect the given number if it is divisible by 10 or not.

Since the last digit of a given number is 0, then the given number is divisible by 10. There's no remainder or a fraction in the division.

You should consider in studying the divisibility of a number because you will use these principles later when you will study higher Math subjects that involves the division of a number, simplifying fractions, and even factoring. 

This method can also be used for negative integers as long as the last digit of a given number is 0. Again, there should be no remainder or a fraction in the division.      
 

Divisibility - 9

Category: Arithmetic

"Published in Newark, California, USA"

Divisibility by 9:

How do you know that a number is divisible by 9? Well, a number is divisible by 9 if the sum of the digits is a multiple of 9, then the given number is divisible by 9. You can repeat the process until the result is a multiple of 9.

Example 1:

The first thing that we need to do is to inspect the given number if it is divisible by 9 or not. Let's add the digits as follows

Since 8 is not a multiple of 9, then the given number is not divisible by 9. There's a remainder of 8 in the division. The answer or a quotient must be a whole number itself. You should not have a fraction or a remainder in the final answer. 

Example 2:

The first thing that we need to do is to inspect the given number if it is divisible by 9 or not. Let's add the digits as follows

 

Since 9 is a multiple of 9, then the given number is divisible by 9. There's no remainder or a fraction in the division.

You should consider in studying the divisibility of a number because you will use these principles later when you will study higher Math subjects that involves the division of a number, simplifying fractions, and even factoring. 

This method can also be used for negative integers as long as the sum of the digits is a multiple of 9. Again, there should be no remainder or a fraction in the division.