Hi there. This is a quick and easy math guide on doubling numbers.
Add By Itself To Get The Double
You could do doubling as in multiplying a number by two. It is easier thought to double a number by adding the number by itself.
Double of 30 for example is 60 as 30 + 30 is equal to 60.
Double of 8 is 16 from 8 + 8.
Working with larger numbers and doubling can be tricky. Double of 157 is 314. You could mentally break the number 157 into 150 and 7. Double of 150 is 300 and double of 7 is 14. Adding these separate doubles gives 314 as 300 + 14 is 314.
A more algebraic example would be doubling something like 7x. Double of 7x is 14x.
Extension - Double The Double To Get Four Times A Number
We can use the fact that double of 2 is four. With this in mind we can double a doubled number to obtain four times the original number.
Four times nine is 36. This is because double of 9 is 18 and double of 18 is 36.
The number 120 quadrupled is 480. Double of 120 is 240 and the double of 240 is 480.