Centimetre.
centimeters
Centimeters or Meters. I'm not sure which.
centimeters
It would be more appropriate to measure a book in centimeters as meters might be too large a unit of measurement for a book. Additionally, centimeters provide a more precise measurement for the size of a book.
Millimeters or centimeters.
you measure the thickness of a book in inches.
Inches or centimeters
Instruments such as calipers, rulers, and tape measures can be used to measure the width of a book. These instruments provide an accurate measurement of the book's width in either inches or centimeters.
What is the most appropriate instrument to measure
Square centimetres and square metres are measures of area in 2-dimensional space: they cannot be used to measure the length of a book cover which is a 1-dimensional measure.
I think I saw that you tried to include that your units were in inches. this is not a metric unit to start. convert inches to centimetres. then multiply the length by the width to get your answer in cm^2, a metric unit
You would typically use centimeters (cm) or millimeters (mm) to measure the width of a book. These units provide a more precise measurement for smaller objects like books.