Lesson 41: Units, Unit Multipliers

Denominate Numbers*: a number with a word that designates units.

For example, 4 feet, 6 centimeters and 93 liters are all denominate numbers. The units are feet, centimeters and liters.

We know that 12 inches = 1 foot so if we write either 12 in. /1 ft We know that 12 inches = 1 foot so if we write either 12 in./1 ft. of 1 ft./12 in. We have written an expression whose value is 1. we can multiply any expression by either of these terms without changing the value of the expression. We call these unit multipliers.

Example: Use a unit multiplier to change 600 inches to feet.

Answer: 600 in. x 1 ft. / 12 in. = 50 feet

Example: Use unit multipliers to convert 44 square feet to square inches.

Answer: 44 ft./1 x ft./1 x 12in./1ft. x 12in./1ft. = (44)(12)(12) in.

Example: Use unit multipliers to convert 42 square yards to square inches.

Answer: 42(3)(3)(12)(12) in. 2

Example: Use unit multipliers to convert 16 cubic miles to cubic inches.

Answer: (16)(5280)(5280)(5280)(12)(12)(12) in Answer: (16)(5280)(5280)(5280)(12)(12)(12) in. It seems there are quite a few cubic inches in 16 cubic miles. 3

HW: Lesson 41 #1-30