Question

In a stack there are $5$ books each of thickness $20mm$ and $5$ paper sheet each of the thickness $0.016mm$. What is the total thickness of the stack?

Answer 1

Hint: In the given question, we have to find out the total thickness of the stack. Stack consists of $5$ books and $5$ papers. Since the thickness of books and papers are given for each. Work out the total thickness of $5$ books and thickness of $5$ papers and then add then thickness. The stack thickness is the total thickness of $5$ books and $5$ papers.

Complete step-by-step answer:
Thickness of each book is $20mm$.
Since, $5$ books are kept, therefore total thickness of $5$ books $ = 20 \times 5 = 100$.
Again, the thickness of each paper sheet is $0.016mm$.
$5$ paper sheets are kept in the stack.
Now, we will have to multiply the thickness of each paper by the total no. of paper sheets.
$\therefore $Total thickness of $5$ paper sheets = Thickness of each paper sheet $ \times 5$
${
   = 0.016 \times 5 \\
   = 0.080mm \\
   = 0.08mm \\
} $
$\therefore $Total thickness of stack consisting $5$books and $5$paper sheets $ = $thickness of $5$ books & thickness of $5$paper sheets.
${
   = (100 + 0.08)mm \\
   = 100.08mm \\
} $

Note: This is a simple question asked from the arithmetic. In this type of question unit conversion plays an important role. The unit used here $mm$, but there was no need to convert from $mm$to any other units. Since, the question was to find. Stack thickness consisting of $5$ books & $5$ paper sheets. So, their thickness gives the required answer.
10mm = 1cm 100cm = 1m 1000m = 1km