a street light may be 10ft tall. How many centimeters is this?

Answer 1

10 ft*(1)*(1)
Multiplying a value times one doesn't change it. What if the one was something, n1, divided by something else, n2, where n1=n2. Still good.

10 ft*(12 in/1 ft)*(2.54 cm/1 in)

12 inches = 1 foot so to multiply by 12 in/1 ft is to multiply by one. But in the process it changes your units to inches and the next step changes it to cm. Got it?

Credit my physics teacher, Doc Schwede.

Answer 2

Well 12 inches to a foot, and 2.54 centimeters to an inch, gives an equation of 10 * 12 * 2.54. Which equals 304.8 centimeters.