While thousands of students around the world take the SAT and ACT every year, these two tests are created primarily with U.S. students in mind, and as a result, test writers sometimes casually introduce units that are uniquely American. However, if you’re an international student, you’re probably more accustomed to using meters than feet, and references to monetary units such as “nickel” and “dime” may leave you feeling lost. Understanding a few key concepts can help you master SAT and ACT math questions that test distance, currency, and time zones.
If you’re from anywhere outside of the United States, you’re probably familiar with the metric system. The metric system makes a lot of sense: each unit is related to each other unit by a factor of ten. A kilometer is 1,000 meters; a meter is 100 centimeters; a centimeter is 10 millimeters. However, the United States uses U.S. customary units—units that may seem arbitrary by comparison and are a holdover from the British Imperial units that were in place when the U.S. was a British colony. Here a few U.S. customary unit/metric conversions:
- Mile: A mile is the unit of measure that Americans use for most long distances. One mile = 1.61 kilometers. However, for the purposes of standardized tests, don’t worry about memorizing this conversion; if you need this information, the test question will provide it.
- Foot: A foot is basically the size of a human foot—if that human had a ginormous foot. More formally, 1 meter = 3.3 feet, so a foot is a little less than a third of a meter. However, this is also not a conversion you’ll need to memorize.
- Inches: An inch is basically as thick as your thumb is. Defined precisely, 1 foot = 12 inches. Many standardized test problems use both measurements in a single problem. It’s not rare to read “The floor is 12 feet by 8 feet, and each tile is 4 by 4 inches.” In this case, convert the floor area to inches (144 by 96 inches) and proceed from there. You will need to memorize the relationship between feet and inches, as test writers typically assume that students already have this information and do not provide the conversion factor.
- Yard: A yard is slightly shorter than a meter. 1 yard = 3 feet, which means that 1 yard = 36 inches. This is another conversion you’ll need to memorize.
Be sure to convert your units before you start calculating the area or volume of a shape! Converting from inches to feet is not the same as converting from inches squared to feet squared, so doing the conversions after you find the area or volume can easily lead to incorrect answers.
You may know that the base currency unit in the United States is the dollar, but do you know the denominations of the U.S. coins? Here are the four pieces of currency you need to understand for the SAT and ACT math sections:
- Quarter: A quarter is worth 25 cents, or $0.25. Keep in mind that $1 = 100 cents, so one-quarter of a dollar is 25 cents—thus the name of the coin.
- Dime: A dime is worth 10 cents, or $0.10.
- Nickel: A nickel is worth 5 cents, or $0.05.
- Penny: A penny is the lowest U.S. denomination and is worth 1 cent, or $0.01.
If you find yourself up against a test question with currency involved, put everything in terms of dollars. So, if a problem asks you, “How much are two pennies, seventeen nickels, nine dimes, and twelves quarters worth?”, write this:
2(0.01) + 17(0.05) + 9(0.10) + 12(0.25) = ?
While time zone conversions work in the same way across the world, you may not be used to calculating time zone changes in your everyday life, or you may be used to much smaller time changes than those in the U.S. Here are the things you need to know:
- New York and Washington, D.C. are on the east coast.
- San Francisco and Los Angeles are on the west coast.
- At any given time, the west coast of the United States is three hours behind the east coast.
When faced with a math problem that involves U.S. time zones, always convert everything to one particular time zone. For example, consider the following question: “A plane leaves NYC at 8 a.m. local time, lands in Los Angeles at 11:20 a.m. local time, and—after 45 minutes on the ground—returns to New York, taking one hour more to fly back as it did to fly to LA. When does it land in New York?”
Here’s one way to write out each leg of the plane’s journey and work the question:
- Leaves at 8 a.m. NYC time → already converted to 8 a.m. eastern time
- Lands in LA at 11:20 a.m. → 2:20 p.m. eastern time (total flight time: 6 hours and 20 minutes)
- 45 minutes on the ground → 3:05 p.m. eastern time
- Returns to NYC → Add on 6 hours and 20 minutes + 1 hour to get 10:25 p.m. eastern time
Using the three tips above relating to distance, currency, and time zones should help you easily answer test questions that involve U.S. customary units. And if you do end up at university in the United States, you’ll know your way around campus a little more easily.
How to answer unit conversion questions
How to answer statistics questions