Botswana PSLE Mathematics flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Place value

The value a digit has because of its position in a number. In 6 254 the 6 is worth 6 000, the 2 is worth 200 and the 4 is worth 4.

Rounding to nearest ten

Look at the units digit. If it is 5 or more, increase the tens digit by 1 and write 0 in the units place; otherwise keep the tens digit and write 0.

Order of operations

The agreed sequence for calculating: brackets first, then powers, then multiplication and division from left to right, then addition and subtraction from left to right.

Highest common factor

The largest number that divides exactly into two or more given numbers. For 18 and 24 the common factors are 1, 2, 3, 6, so the highest common factor is 6.

Equivalent fractions

Fractions that name the same amount. Multiply or divide the numerator and denominator by the same number, so 2/3 = 8/12 and 5/10 = 1/2.

Percentage of an amount

Divide the amount by 100 to find one per cent, then multiply by the required percentage. So 20% of 250 is 250 divided by 100, times 20, giving 50.

Metric length conversions

Length units step by powers of ten: 1 kilometre equals 1 000 metres, 1 metre equals 100 centimetres, and 1 centimetre equals 10 millimetres.

Perimeter of a rectangle

The total distance around the rectangle, found by adding twice the length to twice the width. A 7 cm by 4 cm rectangle has perimeter 22 cm.

Area of a triangle

Half the base multiplied by the perpendicular height. A triangle with base 10 cm and height 6 cm has area 30 square centimetres.

Volume of a cuboid

Length multiplied by width multiplied by height, given in cubic units. A 5 cm by 3 cm by 2 cm box has volume 30 cubic centimetres.

Capacity conversion

One litre equals 1 000 millilitres, and one litre also equals 1 000 cubic centimetres. So 2.5 litres is 2 500 millilitres.

Speed formula

Speed equals distance divided by time. A car covering 180 km in 3 hours travels at 60 km per hour. Rearranged, distance equals speed times time.

Elapsed time

The time between a start and an end. Subtract the start time from the end time, borrowing 60 minutes when needed; 09:40 to 11:15 is 1 hour 35 minutes.

Angles on a straight line

Angles that sit together on a straight line add up to 180 degrees. If one angle is 115 degrees, the other must be 65 degrees.

Angle sum of a triangle

The three interior angles of any triangle always add up to 180 degrees, whatever the shape or size of the triangle.

Isosceles triangle

A triangle with two equal sides. The angles opposite those equal sides are also equal, so if one base angle is 50 degrees the other is 50 degrees.

Alternate angles

When a transversal cuts two parallel lines, the angles in alternate positions on opposite sides of the transversal are equal.

Line of symmetry

A line that folds a shape into two matching halves. A square has 4 lines of symmetry and an equilateral triangle has 3.

Types of angles

An acute angle is under 90 degrees, a right angle is exactly 90, an obtuse angle is between 90 and 180, and a reflex angle is over 180.

Area of a parallelogram

Base multiplied by perpendicular height, not by the slant side. A parallelogram with base 8 cm and height 5 cm has area 40 square centimetres.

Mean of a data set

Add all the values and divide by how many there are. For 4, 7, 7, 10 the total is 28 and there are 4 values, so the mean is 7.

Median of a data set

The middle value once the data are arranged in order. With an even number of values, take the mean of the two middle values.

Mode of a data set

The value that appears most frequently. In 3, 5, 5, 8, 9 the mode is 5; a set may have no mode or several modes.

Range of data

The largest value minus the smallest value. For the data 12, 15, 20, 31 the range is 31 minus 12, which is 19.

Pie chart sectors

A whole pie chart represents 360 degrees or 100 per cent. A sector of 90 degrees is one quarter of the data, and 36 degrees is one tenth.

Pictograph key

A pictograph uses symbols, and the key states what each symbol is worth. If one symbol means 5 books, three symbols mean 15 books.

nth term of a sequence

For a sequence rising by a constant difference, the nth term equals the first term plus n minus 1, all multiplied by the common difference.

Substitution

Replacing letters in an expression with given numbers, then calculating. If a equals 4, then 3a plus 2 becomes 12 plus 2, which is 14.

Solving a simple equation

Do the same operation to both sides to keep balance. To solve x plus 7 equals 15, subtract 7 from both sides, giving x equals 8.

Like terms

Terms with exactly the same letter part. They can be combined, so 5x plus 3x equals 8x, but 5x plus 3 stays as it is.

Triangular numbers

Numbers made by adding consecutive counting numbers: 1, 3, 6, 10, 15. The differences between them increase by one each time.

Unitary method

Find the value of one unit by dividing, then multiply for the required number. If 4 pens cost 20 Pula, one pen costs 5 Pula and 7 pens cost 35 Pula.