You want to put a 5 inch thick layer of topsoil for a new 23 ft by 17 ft garden. the dirt store sells by the cubic yards. how many cubic yards will you need to order? the store only sells in increments of 1/4 cubic yards.

1 yard = 3 feet = 36 in

so 1 in = 1/36 yard,  1 ft = 1/3 yard.

The volume of the layer of the topsoil, is:

5 in * 23 ft * 17 ft = 5 *(1/36)*23*(1/3)*17*(1/3)  yard cubed =

(5*23*17)/(36*3*3)= 1955/324=6.034 yard cubed.

The store only sells increments of 1/4 = 0.25 cubic yards.

we need 6.034/0.25=24.136 

So we need to buy 25 (24 will not be enough) increments of 1/4 cubic yards.

25 increments of 1/4 cubic yard, that is 25*0.25=6.25 cubic yards.

Main idea on left, details on right