Do you need **calculate the double of a number**? You can do it immediately with our online calculator to double any amount, even if it has decimals.

You only have to write the number of the number you want **calculate your double**Select with how many decimal places you want the final result and press the calculate button to know the result.

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## What is twice a number?

The double of a number is equal to its value multiplied by two. In many cases, the calculation can be done from memory and without the need of a calculator, although in complex quantities or with decimal numbers, it is more convenient to use a calculator. **calculator to double a number** as the one we offer you on our website.

## How to teach the double of a number

Teaching the concepts of double and lhalf a number requires the other person to have some knowledge of multiplication and division.

For **teach what is the double of a number**For example, the best thing to do is to take several equal objects and make a graphic example. For example, you can find four pens and ask the following question: If I have 3 pens and I get twice as many pens, how many pens will I have?

This way when you put the six pens on the table to show the result, they will understand it much better. You can practice the same example but changing the number of starting pens so that they try to **calculate what is its double**.

## The double of a number in algebraic language

In mathematics, algebraic language is about expressing a formula with letters and numbers. In this case we want to **write in algebraic language what the double of a number is**The following is our response:

x*2 = 2x

Here are some other examples of algebraic language involving the double of a number:

### Twice a number minus its fourth part

(2x) - (x/4)

### Twice a number minus four-fifths of the same number

(2x) - (4x /5)

### Twice a number minus seven equals 8.

In this case what we have is an equation that, expressed in algebraic language, looks like this:

(2x) - 7 = 8

We leave on the left side the term with the x and on the right side we solve the corresponding operation:

2x = 8 + 7 = 15

We clear the unknown and we have that:

x = 15/2 = 7,5

We can check if the result is correct by returning to the starting equation and substituting the value of x obtained:

(7,5*2) - 7 = 8

Solving, we can see that the result obtained is correct and therefore, the equation is fulfilled.

### Twice a number minus its third part

(2x) - (x/3)

### Twice a number minus one-fifth of a number

(2x) - (x/5)

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