GMAT Arithmetic

Updated March 04, 2010

The GMAT Quantitative Ability section includes Data Sufficiency and Problem Solving Questions. Problem solving questions come in 3 different varieties: Algebra, Geometry, and Arithmetic.

GMAT Arithmetic

Out of the three sections, Arithmetic section usually accounts for over 50% of the questions asked in GMAT quantitative section. Some of the important arithmetic concepts for GMAT are number properties, averages and simple operations, and probabilities.

Number Properties and Operations

Some of the properties of numbers you need to know for the GMAT include:

Integers vs. rational numbers
Prime numbers vs. composites
Fractions and percentages
Even and odd numbers
Perfect squares and radical expressions (roots)

Of course, you will also need to be able to perform simple operations (addition, multiplication, etc.) with these types of numbers in order to simplify expressions or find values.

Examples:

Find the value of $(\sqrt{5} + \sqrt{5}) ^ 2 + (\sqrt{10} + \sqrt{10}) ^ 2$ .

Solving this question requires some knowledge of simple operations in radical numbers and exponent laws. Here’s how you solve this question: $(\sqrt{5}+\sqrt{5})^2+(\sqrt{10}+\sqrt{10})^2=(2\sqrt{5})^2+(2\sqrt{10})^2=(2^2)(\sqrt{5}^2)+(2^2)(\sqrt{10}^2)$ , which equals 4(5)+4(10)=20+40=60 . It’s easy to get confused, so watch out.

X is a prime number that is greater than 21 but less than 42. How many possible numbers can X be?

Here you need to know prime number theory. Going one by one from 21 to 42, you need to check whether each number is prime by trying to factor it. The primes in the range are: 23, 29, 31, 37, 41. Therefore your answer is 5.

$\frac{1}{4}$ is what percentage of $\frac{1}{32}$ ?

Here you need to know fractions and percentages. You need to note that you answer will be more than 100 percent, since 1/32 is less than 1/4. In fact, $\frac{1}{4} = \frac{1}{32} * 8$ . Thus, 1/4 is 800 percent of 1/32.

More Arithmetics

There are more types of arithmetic problems. You need to be able to find averages in various ways. You also need to be familiar with the basics of probability and statistics, as well as permutations and combinations.