How many whole numbers are there in between 19 and 42?

To do:

We have to find the number of whole numbers between 19 and 42.
Solution:

Number of whole numbers between $a$ and $b$(where $b>a$) $=b-a-1$

Therefore,

Number of whole numbers between 19 and 42 $=42-19-1$

$=42-20$

$=22$

 The number of whole numbers between 19 and 42 is 22.