Cameroon GCE O-Level Mathematics key terms

A counting number starting from 1, 2, 3 and continuing without end. It contains no fractions, decimals or negatives, and is used for counting objects and ordering positions.

Any counting number together with zero: 0, 1, 2, 3 and so on. It differs from natural numbers only by including zero and has no fractional or negative members.

A whole number that may be positive, negative or zero, such as -7, 0 or 12. It never has a fractional or decimal part and forms the set used in directed-number arithmetic.

A number that can be written as a fraction a/b where a and b are integers and b is not zero. Its decimal form either stops or repeats a pattern.

A real number that cannot be written as a simple fraction of two integers. Its decimal expansion never stops and never repeats, as with the square root of 2 or pi.

A whole number greater than 1 whose only positive divisors are 1 and itself, for example 2, 3, 5, 7 and 11. One is not prime.

A whole number that divides another exactly, leaving no remainder. For instance 4 is a factor of 12 because 12 divided by 4 gives 3 exactly.

The result of multiplying a given whole number by any integer. Multiples of 6 include 6, 12, 18 and 24, and they continue without limit.

The largest whole number that divides two or more given numbers exactly. Found by listing common factors or comparing prime factorisations of the numbers involved.

The smallest non-zero number that is a multiple of each of two or more given numbers. It is useful when adding fractions with different denominators.

A way of writing very large or very small numbers as a value between 1 and 10 multiplied by a power of ten, such as 3.2 x 10^5 or 4.7 x 10^-3.

The digits of a number that carry meaningful information about its precision. Leading zeros are ignored, so 0.00452 has three significant figures and rounds to 0.0045.

A position of a digit to the right of the decimal point. Rounding to two decimal places means keeping two digits after the point and adjusting the second by the next digit.

Replacing a number by a nearby value with fewer digits, chosen by looking at the next digit. A digit of 5 or more rounds up; anything below 5 rounds down.

A comparison of two or more quantities of the same kind, written with a colon such as 3:5. It shows relative size and can be simplified like a fraction.

A statement that two ratios are equal, or a relationship where quantities change together at a fixed relative size. Used to share amounts and scale recipes or maps.

A relationship in which one quantity increases or decreases at the same rate as another, so their ratio stays constant. Written as y = kx for some constant k.

A relationship in which one quantity grows while the other shrinks so their product stays fixed. Written as y = k/x, where k is a constant.

A fraction or ratio expressed out of one hundred, shown with the percent sign. For example 35% means 35 out of every 100, or the fraction 35/100.

Money paid for borrowing or earned on savings, calculated only on the original amount using I = PRT/100, where P is principal, R the yearly rate and T the time in years.

Interest calculated on both the original amount and previously added interest, so the total grows faster than with simple interest. Usually computed year by year or with a formula.

A small raised number showing how many times a base is multiplied by itself, as the 3 in 2^3 means 2 x 2 x 2. Also called an exponent or power.

An irrational root of a number, such as the square root of 5, left in root form because its decimal never ends. Surds can often be simplified or combined.

A combination of numbers, letters and operation signs with no equals sign, such as 4x + 7y. Letters stand for unknown or variable values and can be simplified or substituted into.

The number multiplying a letter in an algebraic term. In 7x the coefficient is 7, and in -3ab it is -3; a letter written alone has coefficient 1.

Terms that contain exactly the same letters raised to the same powers, so they can be added or subtracted. For example 5x and -2x are like terms, but 5x and 5x^2 are not.

A mathematical statement that two expressions are equal, containing an equals sign and usually an unknown to be found, such as 3x - 5 = 16.

A statement comparing two expressions that are not necessarily equal, using symbols such as <, >, <= or >=. Its solution is a range of values rather than a single number.

Two or more equations that must be true at the same time, solved together to find values satisfying all of them. Common methods are elimination and substitution.

Replacing a letter in an expression or formula with a given number, or replacing one variable with an expression from another equation, then evaluating or solving.

Writing an expression as a product of simpler expressions, such as turning x^2 + 5x + 6 into (x + 2)(x + 3). It is used to simplify fractions and solve quadratic equations.

An equation in which the highest power of the unknown is two, usually written ax^2 + bx + c = 0 with a not zero. It can be solved by factorising, completing the square or the formula.

The value b^2 - 4ac taken from a quadratic equation ax^2 + bx + c = 0. Its sign tells whether the equation has two, one or no real roots.

The values of the unknown that make an equation true. For a quadratic, they are the x-values where the curve crosses the horizontal axis.

An ordered list of numbers following a rule, such as 3, 7, 11, 15. Each number is a term, and the rule may be described by a formula for the nth term.

A sequence in which each term after the first is obtained by adding a fixed number called the common difference, as in 5, 9, 13, 17 where the difference is 4.

A sequence in which each term after the first is obtained by multiplying by a fixed number called the common ratio, as in 2, 6, 18, 54 where the ratio is 3.

A rule that assigns exactly one output value to each allowed input value. It may be shown as a formula, a table, a graph or a mapping diagram.

The steepness of a straight line, found by dividing the vertical change by the horizontal change between two points. A horizontal line has gradient zero.

The point where a graph crosses an axis. The y-intercept is where x equals zero, and the x-intercept is where y equals zero.