Basic Arithmetic for GMAT

The math problems at GMAT are basic from 3 areas: Arithmetic, Algebra and Geometry.

Basic arithmetic operations:

• addition (8+8)
• subtraction (8-4)
• multiplication (8×3)
• division (8/2)
• raising to a power
• finding a square root

Fraction: x/y (part/whole) x = numerator, y = denominator.

Decimals are in English indicated by a point.

Ratio: The whole in ratio is sum of all parts. If ratio is a fraction the whole is the sum of the numerator and the denominator.

Average = total sum of the items/total number of the items.

Arithmetic mean = the process of finding an average.

How to find the Median:

1. first order the numbers from least to greatest
2. if n is odd, median is the middle number
3. if n is even, median is the average of the 2 middle numbers

Mode = the number or the numbers that occur most frequently in a list of numbers.

Range = the greatest value in the numerical data minus the least value.

Standard deviation = measures the distance between the arithmetic mean and the set of numbers.

1. first, find the differences between that average and each one of the set of numbers and square each of the differences
2. second, find the average of the squared differences and take the square root of this average

Frequency distribution: if a,b,c = numbers, f = frequency, av = average.

Standard deviation = √ {[(a-av) ² x f + (b-av) ² x f + (c-av) ² x f]/n.}

Exponents – multiplying, dividing, raising a power to a power, distributing.

In a percentage increase or decrease problem, you must put the amount of the increase or decrease over the original amount.
In compound interest problems, the answer will always be a larger number than it would be in a similar simple interest problem.

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