Suzanna wants to measure a board, but she doesn’t have a ruler to measure with. However, she does have several copies of a book that she knows is 17 centimeters tall.

Suzanna lays the books end to end and finds that the board is the same length as 21 books. How many centimeters long is the board?
Suzanna needs a board that is at least 3.5 meters long. Is the board long enough? Explain.