if 8 boards are stacked on top of each other and each board is 2 1/4 inches thick, how high is the stack?
To find the total height of the stack, we need to multiply the thickness of each board by the number of boards.
Thickness of each board = 2 1/4 inches = (2 + 1/4) inches = 9/4 inches
Number of boards = 8
Total height = (9/4) inches/board * 8 boards = 72/4 inches = 18 inches
The stack is 18 inches high.