How do you write \[\dfrac{{17}}{{20}}\] as a decimal?

Hint: Whenever we need to convert any fractional number to decimal, try to represent the denominator in terms of powers of $10$, which makes calculation easier. This is done because the number of zeros that we represent in terms of powers of $10$ represents the number of digits, after the decimal point.

Complete step-by-step answer:
In the given question they have asked us to convert a fraction number that is \[\dfrac{{17}}{{20}}\] to a decimal number.
Whenever we need to convert any fractional number to decimal, we try to represent the denominator in terms of powers of $10$, which makes calculation easier.
In the given question that is \[\dfrac{{17}}{{20}}\], the numerator represents the upper part of the fraction that is $17$ and the denominator is nothing but the down part of the fraction here it is $20$.
So we try to keep the denominator of the given fraction \[\dfrac{{17}}{{20}}\] in powers of ten, therefore find the equivalent fraction with denominator having multiple of ten, for example, $10,100,1000.....$. So if we multiply $20$ with $5$ then the result will be in terms of powers of ten. To multiply and divide the given fraction by $5$. This is done because the number of zeros that we represent in terms of powers of $10$ represents the number of digits, after the decimal point.
Therefore, we get
\[\dfrac{{17}}{{20}} \times \dfrac{5}{5}\]
\[ \Rightarrow \dfrac{{17}}{{20}} \times \dfrac{5}{5} = \dfrac{{85}}{{100}}\]
As we know that after the decimal point if we have one digit then it represents tenth, if two digits then hundredth and so on. In the same way we can write the above expression as
\[\dfrac{{85}}{{100}} = 0.85\].

Therefore the decimal form of \[\dfrac{{17}}{{20}}\] is $0.85$.

Note: The method we followed is lengthy and it is useful when they ask to convert without using a calculator. Otherwise, we can directly convert by using a calculator also. One important thing we need to remember while following the above steps is that rewriting the denominator as powers of ten to make conversion easier.