DEC Maths Flashcards
1
Q
Fraction of an amount calculation
A
amount/denominator, multiplied by numerator
2
Q
1/2 of 100
A
- 100 / 2 = 50
- 50 x 1 = 50
3
Q
Finding percentage of an amount
A
(TO FIND MULTIPLIER: divide percentage by 100), mutiply amount by multiplier
4
Q
50% of 200
A
- 50 / 100 = 0.5
- 0.5 x 200 = 100
5
Q
Percentage increase
A
- Add percentage increase to 100%
- Find multiplier of total
- Multiply multiplier by amount
6
Q
5% increase of £150,000
A
- 100% + 5% = 105%
- 105 / 100 = 1.05
- £150,000 x 1.05 = £157,500
7
Q
Percentage decrease
A
- Subtract percentage decrease from 100%
- Divide final percentage by 100
- Multiply the multipler by the amount
8
Q
£260 car insurance decreased by 13.5%
A
- 100% - 13.5%
- 86.5%
- 0.865
- £260 x 0.865 = £224.90
9
Q
ratio of 20 apples and 15 oranges
A
20 : 15
(divide both by 5)
4 : 3
10
Q
Area of a square or rectangle
A
A=wl
11
Q
Area of a triangle
A
A = 1/2 × b × h
12
Q
Area of a circle
A
A=πr2
13
Q
Pythagoras
A
a^2 + b^2 = c^2
