# What is 3 4 doubled

## Double numbers

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To double a number we have two ways to do it in our head:

### Double as "add the number to itself"

We add the number to itself, adding the individual digits together.

Example:

### Double as "Multiply the number by 2"

Here we multiply the number by, which is equivalent to adding the number to itself (as shown earlier).

Example:

Calculation:

Every single digit of the number is multiplied with. So

No matter which variant we choose, the end result is the same and the calculations are very similar.

### Carries forward when doubling

We have to make sure that adding or multiplying in places can also lead to carryovers (to the next highest place).

An example is shown below:

### Double the number "746" by adding

The Carry-overs are marked in bold:

 =

### Double the number "479" by means of multiplication

We multiply each digit by, it results:

 times :

### Calculation in the head

If we double the number in our head, it makes sense to split the number down in places (as a sum) and then to double the individual summands.

Example: doubling the number

Now we double each summand:

Then we add the doubled summands together and get the result: