Corey needs 24 boards that are 47 1/2 inches long. how many feet of board should he buy?

An interesting way to think about this is to make use of the associative property of multiplication.

... 24 × 47 1/2 inches = (24 inches) × 47 1/2 . . . . associate inches with the other number

Now, you know that 24 inches is 2 feet, so you can finish the problem

... (2 feet) × (47 1/2) = (2×47 + 2×1/2) feet = 95 feet

Another way to think about this is

... 24 × 47 1/2 inches = 24 × (48 inches - 1/2 inch)

... = 24 × (4 feet - 1/2 inch)

... = 96 feet - 24×1/2 inch

.. = 96 feet - 12 inch

... = 95 feet

The straightforward way to do this is to find the total number of inches, then convert that to feet.

... 24 × 47 1/2 inches = 24×47.5 inches = 1140 inches

Multiplying by the units conversion factor (1 ft)/(12 inches), we get

... (1140 in)×(1 ft)/(12 in) = 95 ft