What Is A Multiple Of 21?

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Introduction

As a professional teacher, one of the concepts that I often teach my students is the concept of multiples. In mathematics, multiples are numbers that can be divided by another number without leaving a remainder. In this article, we will be focusing on multiples of 21.

What are Multiples of 21?

Multiples of 21 are numbers that can be divided by 21 without leaving a remainder. Some examples of multiples of 21 include 21, 42, 63, 84, 105, and so on. These numbers are obtained by multiplying 21 by different integers.

How to Find Multiples of 21

To find multiples of 21, you need to multiply 21 by different integers. For example, to find the first few multiples of 21, you can multiply 21 by 1, 2, 3, 4, and so on. This will give you the following sequence of multiples: 21, 42, 63, 84, 105, and so on.

Applications of Multiples of 21

Multiples of 21 have several applications in mathematics. For example, they are used in finding the least common multiple (LCM) of two or more numbers. The LCM of two numbers is the smallest number that is a multiple of both numbers. To find the LCM of two numbers, you can list their multiples and find the smallest multiple that they have in common.

Properties of Multiples of 21

Multiples of 21 have several properties that make them unique. For example, every multiple of 21 is also a multiple of 3 and 7. This is because 21 is a product of 3 and 7. Additionally, every multiple of 21 is an odd multiple of 3, which means that it is not divisible by 2.

Divisibility Tests for Multiples of 21

There are several divisibility tests that you can use to determine if a number is a multiple of 21. One of the most common tests is to check if the number is a multiple of 3 and 7. To do this, you can add up the digits of the number and check if the sum is a multiple of 3 and 7.

Examples of Multiples of 21

Let's look at some examples of multiples of 21: - 21 is a multiple of 21 because 21 ÷ 21 = 1 - 42 is a multiple of 21 because 42 ÷ 21 = 2 - 63 is a multiple of 21 because 63 ÷ 21 = 3 - 84 is a multiple of 21 because 84 ÷ 21 = 4 - 105 is a multiple of 21 because 105 ÷ 21 = 5

Conclusion

In conclusion, multiples of 21 are numbers that can be divided by 21 without leaving a remainder. They have several applications in mathematics and have unique properties that make them interesting to study. By understanding the concept of multiples of 21, students can develop their problem-solving skills and become more confident in their mathematical abilities.