Question

02
A notebook has total of 540 pages from which 75% are already used. Find the number of unused pages.​

Answer 1

Total number of pages in a notebook=540

Number of pages from this book that are used:-

= 75% of the total number of pages

$= 75 \% \: \: of \: \: 540$

$= \frac{75}{100} \: \: of \: \: 540$

$= \frac{75}{100} \times 540$

$= \frac{75 \times 540}{100}$

$= \frac{40500}{100}$

$= \bold{405 \: pages}$

Thus, the number of pages from this notebook that have been used=405 pages

Number of pages from this notebook that are unused:-

$= 540 - 405$

$= \bold{135 \: pages}$

Thus, the number of pages from this notebook that have not been used=135 pages

Now let us check whether or not we have found out the correct number of unused pages in the notebook by checking if or not 25% of 540 is 135:-

$= 25 \% \: \: of \: \: 540$

$= \frac{25}{100} \: \: of \: \: 540$

$= \frac{25}{100} \times 540$

$= \frac{25 \times 540}{100}$

$= \frac{13500}{100}$

$=\bold{ 135 \:pages }$

As 25% of 540 is resulting in 135 we can conclude that we have found out the correct number of unused pages.

Therefore, the number of unused pages in the notebook =135