It depends on how many decimal places there are.
If it has one decimal place, like 0.2, it's called 'two tenths' or 2/10.
If it has two decimal places, like 0.34, it's called 'thirty-four hundredths' or 34/100.
If it has three decimal places, like 0.842, it's called 'eight hundred forty-two thousandths' or 842/1000.
And so on...
Afterwards you can simplify the fraction by finding the greatest common factor(GCF) of the numerator and denominator, then dividing the numerator and denominator by that number.
