**Hint:** one-fifth of \[x\] is \[\dfrac{1}{5} \times x = \dfrac{x}{5}\]

There are five \[\dfrac{x}{5}\]’s in \[x\]

So, number of one fifth is \[5\]

**Complete step by step solution:** A fraction tells you how many parts of a whole you have. When you divide something into two equal parts, each part is called a half. When you divide a whole object into four equal parts, each part is called a quarter. The top number is called a numerator. This shows how many parts you have. The bottom number is called a denominator. This shows you how many parts the whole object has been divided into.

Fractions represent equal parts of a whole or a collection.

Fraction of a whole: When we divide a whole into equal parts, each part is a fraction of the whole.

One-fifth of \[1\] is \[\dfrac{1}{5} \times 1 = \dfrac{1}{5}\]

There are five \[\dfrac{1}{5}\]’s in \[1\]

So, number of one fifth in \[1\] is \[5\]

And, the number of \[\dfrac{1}{5}\]’s in \[100\] will be \[5{\text{ }} \times {\text{ }}100{\text{ }} = {\text{ }}500\]

\[5\] one fifth make one unit .so \[100\] is made up of hundreds into five answer will be \[500\]

**Note:** With whole numbers only, we cannot always say precisely how long something is. Fractions were invented for that purpose. You should learn to calculate with fractions.Fractions are really important and we use them lots in daily life.We use them when telling the time to know when it is 'quarter past', 'half past' and 'quarter to' the hour.We use them when we’re baking, for example 'use half a kilogram of flour'.