Number section Flashcards
To remember everything covered on this section
BIDMAS
Brackets, Indices, Division, Multiplication, Addition, Subtraction.
Use for order of operations.
Multiply by 10
Move decimal point one space to the right. E.g. 23.6=236.
Or add a zero on the end if no decimal point E.g. 45x 10=450
Divide by 100
Move decimal point two places to the left e.g 34.5/100=0.345
Divide by 20
Divide by 2 first then divide by 10
Multiply by 300
Times by 3 then times by 100
Negative number multiplied by negative number =
Positive number
Positive number multiplied by negative number =
Negative number
5 - -4=
5+4=9
Divide a decimal by a whole number
Use bus stop method. Put decimal point on top of bus stop.
Divide a number by a decimal
Write as fraction. Then times by 10, 100 etc to get rid of decimal point.
The first prime number is
- It is NOT 1!!!!!
The only even prime number is
2.
How to find a prime number from a list of numbers.
Get rid of all the even numbers and anything ending in a 5. Then divide by 3 and 7, if it doesn’t divide by either it is prime.
First 4 prime numbers
2,3,5,7
What is a multiple?
Just the times table of a number. Eg first 4 multiples of 2 are 2,4,6,8
What is a factor?
All the numbers that divide into another number. Eg 4 is a factor of 24 as you can divide 24 by 4
What is an integer?
A whole number
How to multiply fractions
Just multiply top numbers together, then multiply bottom numbers together
How to divide fractions
Switch the second fraction to upside down then multiply
How to add or subtract fractions
Need to put both fractions over the same bottom number (common denominator) then add or subtract bottom numbers
How to change a decimal to a percentage
Times by 100
How to change a percentage to a decimal
Divide by 100
Estimating without using a calculator
Round all numbers in calculation to 1 significant figure
When multiplying numbers with indices
Add the powers. Eg 3^4 x 3^6 = 3^10.
When dividing numbers with indices
Subtract the powers
13 x 13
169
14 x 14
196
15 x 15
225
