What are the 10 perfect squares

Divide the width of the shelf by the widthof the books.

First rewrite feet as inches:

1 foot = 12 inches.

3 1/2 feet x 12 inches per foot = 42 inches

Now divide the width of the shelf by the width of the book:

Now you have 42  /  5/8

When dividing by a fraction flip the second fraction over and change division to multiplication:

42 x 8/5

Now Multiply across:

7/2 x 8/5 = (42 x 8) /5 = 336/5 = 67.2

Round to the nearest whole number: 62

The shelf will hold 62 books.