# What Is an Annex in Math? ••• Hemera Technologies/AbleStock.com/Getty Images

Annexes in math may sound complex but they are in fact very simple. However, the word "annex" has multiple meanings, which can make it confusing. Annexing a number to either side of an equation may involve either adding or multiplying. Annexing may be useful when attempting to solve algebra.

If you start off with the equation: 2x + 6 = 4y + 16 You may add a number to either side of the equation. For example, you may add 4 to either side: 2x + 10 = 4y + 20 Here annexing simply means adding.

## Annexing by Mulitplication

If you start off with the equation: 44,670 x 5 = 223,350 You can multiply either side of they equation by annexing zero: 446,700 x 5 = 2,233,500 In this case annexing means multiplication.

## Purpose of Annexing by Addition

Annexing a number to either side of the equation makes it possible to complete the equation. For example: 2x + 10 = 4y + 20 Rearranging gives you: 2x - 4y = 20 -10 = 10

## Purpose of Annexing by Multiplication

If you are asked to make the following calculation: 44,670 x 5 = You may find it easier if you multiply either side of the equation by annexing 0: (44,670 x 10) / 2 = 446,700 / 2 = 223,350 This method is helpful if you find it easier to divide by 2 than to multiply by 5. In many cases this will be true, and annexation can therefore be a useful technique.

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