•Organized method of problem-solving •Used in chemistry, physics, engineering, and medicine •Communicates the path to scientists that follow your work •Records your own path for your future use

Unit conversion factor

A unit conversion factor is a fraction whose numerator and denominator are equal measures. Some common unit conversion factors are given below. You can also use the reciprocal (opposite order) of these.

•Calculate the number of minutes in 3.61 hours.

*Note: Use the number given in the question to determine the number of sig figs in your answer.

3.61 hr 60 min 1 hr = 216.6 min = 217 min

How many centimeters are in 4.2 inches?

There are 2.54 centimeters in an inch.

*Note: Use the number given in the question to determine the number of sig figs in your answer.

4.2 in 2.54 cm 1 in = 11 cm

•Calculate the number of 261 grams is how many kilograms? 1 kilogram = 1,000 grams.

*Note: Use the number given in the question to determine the number of sig figs in your answer.

261 grams 1 kilograms 1,000 grams = .261 kilograms

•Calculate the number of 150 pounds is how many kilograms? 1 pound = .4535 kg.

*Note: Use the number given in the question to determine the number of sig figs in your answer.

150 lbs .4535kg

= 1 Ibs 68.0 kg

Calculate the number of seconds in two weeks.

2 Wk 7 days 1 Wk 24 hours 1 day = 336 hours