Åk 6–9
 
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7.2 Decimals in the Denominator
If you are unsure what is meant by denominator, you can look back on the fraction section, chapter 2.3. A denominator is the number you divide by, in other words the number underneath the fraction line.

A simple way to think about this is to ask yourself how many times the denominator goes into the numerator.  This is called “content division” (innehållsdivision).


Example A

Kalle buys a 1 m long ribbon that he is going to cut into 0.20 meter long pieces.  How many pieces will he get?

This exercise is written with digits (0.2 is the same as 0.20):
= ?
The question that we can ask is: “how many times does 0.2 go into 1?” We write this as multiplication:

0.2 · ? = 1

The answer becomes 5.  Kalle gets 5 pieces with the length 0.20 m.

So:
= 5



Example B

A method which usually simplifies division with decimals is called expansion.
= 20
Here you can think like this: “How many times 0.5 is 10?”


If you think that this is difficult, extend 10 ÷ 0.5 by multiplying 10 in both the denominator and the denominator so that the denominator becomes a whole number:
= = = 20