# Math Vocabulary!

When we think of vocabulary, we most often think of the reading component of the SAT and ACT. Yet, understanding vocabulary is just as important for acing the math section of these tests. Below are some key math vocabulary terms. Perhaps you don’t need flash cards, but you do need to practice putting these terms to use on the exams.

#### PRIME

A number that can’t be divided by anything except itself and 1, such as 2, 3, 5, 7, 11, 13, and 17.

Note: Yes, 2 is a prime number, but 1 is not. Also, beware of numbers that look prime but aren’t, such as 51 (divisible by 3 and 17).

#### FACTOR / MULTIPLE

The factors of 10 are 1, 2, 5, and 10.

Some multiples of 10 are 10, 20, 30, 40, and 50.

People confuse these two words all the time. Just think “multiple” means you should “multiply” the number.

#### REMAINDER

What? You haven’t done remainders since second grade? Nonetheless, remainders are often on the SAT.

When you divide 19 by 5, the remainder is 4. This is because the closest multiple of 5 (without overshooting) is 5×3=15. That’s 4 below 19.

(If you still remember long division, you can also use that to find remainders.)

Note: 19 ÷ 5 = 3.8, but the remainder is not 8. Forget about the decimal when finding remainders.

#### ARITHMETIC MEAN / MEDIAN / MODE

“Arithmetic mean” is a fancy word for average.

“Median” is the middle number (be sure to put the numbers in order first). Think “highway median,” which is the white line down the middle of a highway.

“Mode” is the most frequent number. Think “a la mode,” which means fashionable or popular.

#### DOMAIN / RANGE

“Domain” means all the possible x-values of a function. “Range” means all the possible y-values of a function.

Generally, if you’re given the equation of a function, it’s best to graph it on your graphing calculator. Use the picture to determine the domain and range, rather than algebra.