Facts And Terms Flashcards
Factor
A whole number that goes into another number without remainder.
Multiple
Any numbers that are in the times table.
Prime
A number that has exactly two factors; one and itself.
LCM
Lowest Common Multiple.
HCF
Highest Common Factor.
Writing a number as product of primes
Use prime factor trees to find prime factors. Write them in a single line using multiplication (and powers if we choose.
How do you find the HCF when using a venn diagram?
Multiply the middle.
How do you find the LCM when using a venn diagram?
Multiply everything.
Factor decomposition
Product of primes
Dividing decimals
Use bus stop method when we know the times table. Include the decimal point in the same place and add in extra o’s as needed.
Negative numbers: adding and subtracting
5 - 6 = ?, 5 + -6 = ?
8 - -3= ?, 8 + 3 = ?
When there are 2 signs in the middle of the sum the operation changes and the second number becomes positive.
5 - 6 = -1, 5 + -6 = -1
8 - -3= 11, 8 + 3 = 11
Negative numbers: multiplying and dividing
- 4 x 2 =
- 3 x 8 =
- 12 / -2 x -3 =
- 20 / 5 x -2 =
If there is an odd number of negative signs in the sum the answer is negative, if there is an even number the answer is positive.
- 4 x 2 = 8
- 3 x 8 = -24
- 12 / -2 x -3 = -18
- 20 / 5 x -2 = 8
Anything to the power of 0 is…
1.
(Indices) Negative power -
Reciprocal is …
Negative power - reciprocal
Reciprocal is 1/number
Rules for indices - multiplying
a^m x a^m = a^m+n
Rules for indices - dividing
a^m / a^n = a^m-n
Indices (a/b)
A -
B -
A - new power
B - root
Rules for indices - brackets
(a^m)^n = a^mn
Calculating with standard form: multiplication
(4 x 10^6) x (5.1 x 10^3) =
x value + power
(4 x 5.1) x (10^6 x 10^3) = 2.04 x 10^10
Calculating with standard form: addition/subtraction
(4.7 x 10^3) + (2.1 x 10^2) =
Convert + or -, convert to standard form
= 4910 = 4.91 x 10
Calculating with standard form: division
3.6 x 10^4) / (9 x 10^6
(3.6/9) x (10^4 x 10^6) = 0.4 x 10^-2 = 4 x 10^-3
Divide values, - powers
Calculating with standard form: using brackets
(2 x 10^4)^3 =
Do the power to each part
2^3 x (10^4)^3 = 8 x 10^12
Expanding brackets
Times inside by outside.
Factorising
Means put back into brackets.
Interior angle
Angle inside the shape.
Exterior angle
Angle made from extending the side.
Regular shape
All angles and sides are equal.
Interior + exterior
= 180 degrees
Sum of interior
180(n-2)
Sure of exterior angles
360 degrees, no matter how many sides.
Each interior angle of regular shape =
(n - 2) x 180)/ n
Quadratics have…
Two answers
E.g. x = 8 or x = -2
Expression
3x + 3y
Equation
3x + 4 = 12
Identity
3(2x + 3) = 6x + 9
Variable
Y
Formula
r = 3x + 3y
Rearranging formulae
It is just like rearranging an equation. Rather than working to get an answer. We end up with algebra.
Write r terms of a means …
Make r the subject or r =
Percent means out of…
100
Multiplier
The percentage of an amount we want, but as a decimal.
If you want to get to the original amount you…
Divide by the multiplier.
If you want to get to the amount afterwards you …
Multiply by the multiplier.
If you increase something by 10%, then decrease that by 10% would you get the same as decreasing by 10% then increasing by 10%?
Yes.
Reverse percentages
Find the original amount after an increase or decrease. Get back to how much 100% is.
Percentage increase and decrease
Increase - add % to original
Decrease - take % from original
Find % first then + or -.
Simple interest
Interest is calculated from original amount. Same amount added on every time.
Compound interest
Interest is based on what is in there at that time.
Direct proportion
As one value increases the other increases by the same rate (doubled / x 10 / quartered).
Inverse proportion
As one value increases by a rate, the other decreases by the same rate (x2 and /2 or /5 and x5 or x8 and /8)
Other phrases for direct proportion
. Directly proportion to . Is proportional to . Varies directly . Y ∝ x . Y = kx
Other phrases for inverse proportion
. Inversely proportional to
. Varies inversely
. Y ∝ 1/x
. Y = k/x
Types of average
Mean, mode and median.
Mean
Add them all up and divide by however many there are (can be a decimal, doesn’t have to be in the list).
Mode
Most common (can have either no mode, 1 value or 2 values. Must be in list).
Median
The middle number when they’re in order (can be a decimal - in middle of two values on list or value on list).
Quartiles:
Split data up into quarters.
How do you find the median?
(n+1) / 2 or 1/2n + 0.5
In the formula for finding the median, what is n?
The number of values in the list.
IQR =
UQ - LQ
How do you find LQ?
(n+1) / 4
How do you find UQ?
3((n+1) / 4)
How do you find the mean from a table?
Sum of fx / sum of f
How do you find modal class/ mode from a table?
The one with the most frequency.
How do you find median from a table?
Sum of frequency + 1 / 2
This gives the place of the value
How do you find the estimate of median (When the table is in classes and answer is a number)?
. Find median class and the place of the value. . Amount of numbers in (to get to the place of the value) / frequency of class. . Then times that by the class width . Add that onto the lowest value of the class.
How do you know whether something is terminating or recurring?
A terminating fraction is a fraction that’s denominator has only 2 and 5 as prime factors.
Irrational
Cannot be expressed as a fraction: surds, pi, e.