DEC Maths

Question 1

Fraction of an amount calculation

Answer 1

amount/denominator, multiplied by numerator

Question 2

1/2 of 100

Answer 2

1. 100 / 2 = 50
2. 50 x 1 = 50

Question 3

Finding percentage of an amount

Answer 3

(TO FIND MULTIPLIER: divide percentage by 100), mutiply amount by multiplier

Question 4

50% of 200

Answer 4

1. 50 / 100 = 0.5
2. 0.5 x 200 = 100

Question 5

Percentage increase

Answer 5

1. Add percentage increase to 100%
2. Find multiplier of total
3. Multiply multiplier by amount

Question 6

5% increase of £150,000

Answer 6

1. 100% + 5% = 105%
2. 105 / 100 = 1.05
3. £150,000 x 1.05 = £157,500

Question 7

Percentage decrease

Answer 7

1. Subtract percentage decrease from 100%
2. Divide final percentage by 100
3. Multiply the multipler by the amount

Question 8

£260 car insurance decreased by 13.5%

Answer 8

1. 100% - 13.5%
2. 86.5%
3. 0.865
4. £260 x 0.865 = £224.90

Question 9

ratio of 20 apples and 15 oranges

Answer 9

20 : 15
(divide both by 5)
4 : 3

Question 10

Area of a square or rectangle

Answer 10

A=wl

Question 11

Area of a triangle

Answer 11

A = 1/2 × b × h

Question 12

Area of a circle

Answer 12

A=πr2

Question 13

Pythagoras

Answer 13

a^2 + b^2 = c^2