# Maths- Number

All number topics on maths that i need 4 GCSE

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• Created by: hhh
• Created on: 01-03-11 20:51

## Integers

Common Factors and Multiples

KEY Points

If you can divide 1 number by another the second is a FACTOR of the 1st

If you multiply 1 number by another the result is a multiple of both the 1st and 2nd numbers

Prime Numbers

Numbers that no factor other than 1 and themselves. These are PRIME NUMBERS For Example- 2, 11 and 29 are prime numbers

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## Powers & Roots

SQUARE AND CUBE ROOTS

KEY POINTS

A square root of a number must be squared (multiplyed by itself or raised to the power of 2) to give the number_ ANY positive number has 2 square roots- 1 positive, 1 negative

The cube root of a number has to be cubed (raised to the power of 3) to give the number.

STANDERED INDEX FORM

Index Notation useful for showing very large and very small numbers

14 000 000= 1.4 (number between 1 and 10)*10*10*10*10*10*10= 1.4*10_6

(Underscore on previous line means 10 to the power of 6)

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## Percentages

To change a percentage into a fraction write over 100 and cancel any common factors   EG 20%= 20/100= 1/5

To change a fraction to percentage multiply by 100%

2/5*100%=2*20%=40%

To find the result of percentage increase or decrease multiply by (1+or-the percentage divided by 100)

42% increased by 23%= 42*1.23=51.66     OR

68 decrease 35%= 68*0.65=44.2

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