You can find a lot of information online about the GMAT. I will only write what I thought it was important. Although most of the information required for the math part is basic, I was surprised to notice that time passed and my knowledge about math was fuzzy sometimes and I also need it an update of the English equivalents of the terms used.

Integers = negative or positive numbers. Do not include fractions.
= odd or even.

a=b x q + r (q=quotient r=remainder)
Distinct numbers = cannot be equal
Prime numbers = a positive integer that has exactly 2 different positive divisor (1 and itself). 0 and 1 are not prime numbers
Absolute value of 5 is |5|

Divisibility rules:

• 6 is divisible by 2
• the factors of 20 are 1,2,4,5,10
• 20 is a multiple of 4

Remember:
Most problems at GMAT require more than one step in getting the right answer!
If you are not a native English speaker learn the technical terms!

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Before starting to write, at the analysis of an argument essay for GMAT, you must read the text carefully and identify the assumptions.

Paragraphs (as in the post about analysis of an issue):

1. Write the argument (copy/paste) and point the three weak points you identified.
2. Write the first weak point and write one reason ore more reasons why it is not true.
3. Write the second weak point and write one reason ore more reasons why it is not true.
4. Write the third weak point and write one reason ore more reasons why it is not true.
5. Write again the three weak points and say that because of those the argument is not “entirely logically persuasive”.

As an example:

1. The argument that … is based on … but omits certain important concerns that must be addressed to make this argument logically persuasive. The declaration that follows the explanation of what … simply explain …. This alone does not support the main argument.
2. First the argument assumes that … But …
3. Second the argument never concentrates on … Although …
4. Finally, the argument also does not deal with … However …
5. Thus the argument is not completely persuasive. The argument would have been more comprehensive and compelling if …

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What I discovered using the 2005 edition of “Cracking the GMAT” (The Princeton Review) was that algebra problems can be solved without using algebra, but an easier method: plugging in.

Basically you just replace with number the unknown data represented with letters. Sounds stupid, but it works and you gain time.

Plugging in a number in the question:

1. Pick one or more numbers to replace the letters in the problem (question)
2. Using your numbers, find an answer to the problem
3. Plug your numbers into the answer choices to see which choice equals the answer you found in step 2

Plugging in a number in the answers:

1. Always start with answer C. Plug that number into the problem and check if it gives you a solution.
2. If choice C is too small, choose the next larger number
3. If choice C is too big choose the next smaller number

If the question contains “must be”, “could be” or “cannot be”, the problems can be solved by plugging in but you may need to plug more than one number.
You must have at least as many distinct equations as you have variables for the equation to be solvable.

ax² + bx + c = 0

x = [-b +/- √ (b²-4ac)] / 2a

Also, simultaneous equation can be solved an addition or subtraction of one equation from the other. This way you can eliminate one of the unknowns.

GMAT’ “most wanted”:

• (x + y) ² = x² + 2xy + y²
• (x + y)(x – y) = x² – y²

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What you need to remember is that GMAT geometry problems always involve more than one step and that when a GMAT problem offers you just a ratio as answer, without any numbers to start from, you need to plug-in any number in the formulas you use.

Some basic tools refer to remembering number replacement and measurements used by GMAT.

• You need to memorize the following approximations: Π = 3, √1 = 1, √2 = 1.4, √3 = 1.7, √4 = 2
• For those used with the metric system memorize this: 12 inches = 1 foot and 3 feet = 1 yard

Also any drawings that have written next: “not drawn to scale” can not be measured.

Going back to the uses that the people which are not native English speaker:

• Line = straight line that extends without end in both directions
• Line segment = part of a line from one point to another
• Right angle = 90
• Perpendicular lines = two lines intersect at right angles
• Parallel lines = two lines in the same plane that do not intersect
• Polygon = closed plane figure formed by three or more line segments called sides
• Vertices = point of intersection of the sides
• Triangle = 3 sides polygon
• Quadrilateral = 4 sides polygon
• Pentagon = 5 sides polygon
• Hexagon = 6 sides polygon
• 180 degrees = sum of the interior angle measures of a triangle
• (n-2) x 180 degrees = sum of the interior angle measures of a polygon with n sides

Degrees and angles

• 360 degrees = circle.
• 180 degrees = line

When two parallel lines are cut by a third line, there appear to be eight separate angles, but there are really only two.( If you do not understand that, maybe is time for you to “Google” some more)

Triangles

• One side of a triangle can never be longer than the sum of the lengths of the other two sides of the triangle, or less than their difference
• Equilateral = all sides of equal length (the angles are also equal)
• Isosceles = two sides of the same length
• Right triangle = a right angle (opposite side = hypotenuse, the others = legs)
• Perimeter = the sum of the lengths of the three sides
• Area = (base x altitude)

Pythagorean Theorem = in a right triangle, the square of the hypotenuse equals the sum of the squares of the other sides.

a² + b² = c²

3 – 4 – 5; 6 – 8 – 10; 12 – 5 – 13; 12 – 9 – 15

A right isosceles triangle: 45 – 45- 90 = 1: 1: √2

A 30 – 60 – 90 triangle: 1: √3: 2

Circles

• Circle = a set of points in a plane that are all located the same distance from a fixed point (the center)
• Chord = a line segment that has its endpoints on the circle
• Diameter = a chord that passes through the center of the circle
• Radius = a segment from the center of the circle to a point on the circle (r)
• Length of an arc of the circle = the degree of the arc/360
• Tangent to a circle = a line that has exactly one point (point of tangency) in common with a circle
• Circumference = the distance around the circle. C = 2 Π r
• Area A = Πr²

Rectangles, squares and other four-sided objects

• Parallelogram = a quadrilateral with both pair of opposite sides parallel. Area = base x heights
• Rectangle = Parallelogram with right angles. Area = length x width
• Square = rectangle with all sides equal
• Trapezoid = a quadrilateral with two sides that are parallel. Area = small base x big base x height/2

Solids, volume and surface area

• Rectangular solid = a three dimensional figure formed by six rectangular surfaces.
• Area = sum of the areas of all the faces
• Volume = length x width x height

Cylinder

• Area = 2 Π r² + 2 Π r h
• Volume = Π r² h

Coordinate geometry - Coordinate plane

• X – Axis = horizontal line
• Y – Axis = vertical line
• Point 1 = (x1, y1); point 2 = (x2, y2)

Line in a coordinate plane: y = m x + b

b = y- intercept. m = slope.

m (slope) = (y2-y1) / (x2-x1)

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