Åk 6–9
 
English/فارسی
7.1 The Unknown Factor
We begin by looking at an example with whole numbers.
= ?
When you divide, you can also say that you are doing a sort of reverse multiplication.

If you change the question and write it as multiplication, you can write it as:

5 · ? = 10

We are looking for a factor multiplied by 5 that becomes 10. The answer is naturally 2, in other words 5 · 2 = 10, which is also the answer to the division: 10 ÷ 5 = 2

Here we have found the answer to division by finding the unknown factor (2) in multiplication.



Here is an example with decimal numbers:
= ?
Here you can then think, “which number should I multiply 0.2 with in order to get 0.6?”

If you write it as multiplication it becomes:

0.2 · ? = 0.6

The answer is 3, in other words 0.2 · 3 = 0.6.
So 0.6 ÷ 0.2 = 3.