# Maths everything

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• Created by: Katieplod
• Created on: 25-05-16 22:00
What are the multiples of 20?
20, 40, 60, 80, 100, 120 ...
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What are the factors of 20?
1, 2, 4, 5, 10, 20
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How do you find 50% of a number?
÷ 2
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How do you find 25% of a number?
÷ 4 (or half it and half again)
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How do you find 10% of a number?
÷ 10
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How do you find 1% of a number?
÷ 100
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How do you find 5% of a number?
Find 10%, then half it.
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How do you find 20% of a number?
Find 10%, then double it.
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How do you find 75% of a number?
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How do you 'square' a number?
Multiply it by itself. e.g. 5² = 5 x 5 = 25
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How do you 'cube' a number?
Multiply it by itself and by itself again. e.g. 2³ = 2 x 2 x 2 = 8
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What is the sum of the angles in a triangle?
180⁰
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What is the sum of the angles in a quadrilateral? (four sides)
360⁰
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What is the sum of the angles in a pentagon? (five sides)
540⁰
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What is the sum of the angles in a hexagon?
720⁰
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How do you find the area of a triangle?
base times height
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How do you find the area of a rectangle?
Length times width
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How do you find the circumference of a circle?
π x diameter (or 2πr) (3.14)
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How do you find the area of a circle?
π x r² (πr²)
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How do you find a fraction of an amount? (e.g. ¾ of 20)
Divide by the bottom, times by the top. (e.g. 20 ÷ 4 = 5 5 x 3 = 15)
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What does a parallelogram look like?
A slanted shape
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What does a trapezium look like?
Two sides caving in
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What are the first 10 square numbers?
1, 4, 9, 16, 25, 36, 49, 64, 81, 100
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What are the first 10 prime numbers?
2, 3, 5, 7, 11, 13, 17, 19, 23, 29
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What are the first 5 cube numbers?
1, 8, 27, 64, 125
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What is a prime number?
A number divisible only by 1 and itself. e.g. 7 is a prime number as it's factors are 1 and 7. 9 is not a prime number as it's factors are 1, 3 and 9.
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How do you calculate the mean?
Add up all the values and divide by how many values there are.
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How do you calculate the range?
Highest value subtract smallest value
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How do you find the median?
Arrange all the numbers in order, then find the middle value.
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How do you find the mode?
It is the most common value (or item)
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A line from the centre of the circle to the circumference
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What is a diameter?
A line from one side of the circle to the other, passing through the centre.
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What is an arc?
An arc is part of the circumference.
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What is a tangent?
A straight line that touches a circle.
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What is a chord?
A line joining two points on the circle, but not passing through the centre (that is the diameter).
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What is a sector?
The region bound between two radii and the arc.
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What is a segment?
The region between a chord and an arc.
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What is ½ as a decimal?
0.5
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What is ¼ as a decimal?
0.25
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What is ¾ as a decimal?
0.75
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What is ¹/₅ as a decimal?
0.2
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What is ¹/₁₀ as a decimal?
0.1
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What is ³/₁₀ as a decimal?
0.3
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What is ⁴/₅ as a decimal?
0.8
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How do you convert decimals to percentages?
Multiply the decimal number by 100 and add the % symbol.
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How do you convert percentages to decimals?
Divide the percentage by 100.
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How do you convert percentages to fractions?
Write the percentage over 100 and simplify.
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How do you convert fractions to decimals?
Divide the numerator by denominator
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How do you convert decimals to fractions?
Remember 0.1 is one-tenth, 0.01 is one-hundredth etc. e.g. Write 0.7 as a fraction. As this is seven-tenths, it would be ⁷/₁₀
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How do you convert fractions to percentages?
Method 1) Find an equivalent fraction with 100 on the demoninator. The numerator is the percentage. Method 2) Divide numerator by denominator to find the decimal. Then multiply by 100.
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How do you multiply fractions?
Multiply numerators and multiply denominators. Simplify if you can.
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How do you divide by a fraction?
Multiply by the reciprocal of the second fraction.
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Make both fractions have a common denominator, then add.
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What is a reciprocal?
You find a reciprocal by "flipping" over a fraction. A number multiplied by it's reciprocal is 1.
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What is a negative X a negative?
Positive. e.g. -4 x -2 = 8
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What is a positive X a negative?
Negative. e.g. 5 x -3 = -15
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What is a negative X a positive?
Negative. e.g. -10 x 2 = -20
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How do you find the angles when drawing a pie chart?
1. Add up the frequencies. 2. Divide 360 by the total frequency 3. Multiply each frequency by that number.
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How many centimetres are in 1 metre?
100
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How many millimetres are in 1 centimetre?
10
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How many metres are in 1 kilometre?
1000
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How many grams are in 1 kilogram?
1000
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How many kilograms are in 1 tonne?
1000
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How many millilitres are in 1 litre?
1000
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How many cm³ are in 1 litre?
1000
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How many inches are in 1 foot?
12
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How many feet are in a yard?
3
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How many pounds are in 1 stone?
16
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What does an acute angle look like?
An acute angle is an angle less than 90 degrees.
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What does an obtuse angle look like?
An obtuse angle is greater than 90 but less than 180 degrees.
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What does a reflex angle look like?
A reflex is greater than 180 degrees
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What do the angles add up to in a right angle?
90 degrees
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What do the angles on a straight line add up to?
180 degrees
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What do the angles at a point (full circle) at up to?
360 degrees
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What are vertically opposite angles?
When two lines cross, the opposite angles are equal. They are called vertically opposite angles.
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What is an isosceles triangle?
A triangle with two equal angles and two equal length sides.
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What is a right-angled triangle?
A triangle with a 90 degree angle.
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What is a scalene triangle?
A triangle where all angles are of different size and all sides are of different length.
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How is the bearing of A from B found?
1. Join A and B with a straight line. 2. Draw a North line at B 3. Measure the clockwise angle from the North line to the line that joins A and B.
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What does tessellate mean?
Identical shapes fit together with no gaps.
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How do you write a number as a product of primes?
two numbers that times together to make the main number
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How do you calculate 'percentage change?'
change ÷ original x 100
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How do you expand brackets?
Multiply the terms inside, by the term outside.
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How do you find the area of a parallelogram
Base times height
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How do you find the area of a trapezium?
It is on the formula sheet and is ½(a+b)h
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## Other cards in this set

### Card 2

#### Front

What are the factors of 20?

#### Back

1, 2, 4, 5, 10, 20

### Card 3

#### Front

How do you find 50% of a number?

### Card 4

#### Front

How do you find 25% of a number?

### Card 5

#### Front

How do you find 10% of a number?