Question

Write the number 1.8 in the form a/b, using integers, to show that it is a rational number.

Answer 1

1.8 = 1 8/10 = 18/10 = 9/5

Answer 2

1. Note that the number 1.8 consists of two parts 1 and 0.8.

2. The decimal 0.8 can be written as the fraction
`(8)/(10).`

3. Add these two numbers:

`1+(8)/(10)=(10)/(10)+(8)/(10)=(10+8)/(10)=(18)/(10).`

4. Since 18=2·3·3 and 10=2·5, the fraction
`(18)/(10)` can be simplified to the rational number

`(18)/(10)=(2\cdot 3\cdot 3)/(2\cdot 5)=(3\cdot 3)/(5)=(9)/(5).`