Thursday 30 April 2020

Primary Maths : Notes and Formulae

NUMBERS
Place Values
Value is the positional value of the digit in the number or where the digit is in the number.  
Digits are symbols or characters to represent a number in writing.

Rounding
RULE for rounding off
If number is from 0 and to 4, then DROP or Fall (4) off / let it go
If number is from 5 to 9, then ADD 1 or high 5 --> go higher
Estimate
Rounding numbers is a way of estimating numbers

Dividing Whole Numbers By Tens, Hundreds, And Thousands
When any whole number is DIVIDE by 10100, or 1000
                        we REMOVE’ or CANCEL’ the corresponding 0s to the number.

Quotient And Remainder
 There are special names for each number in a division.
                             12 ÷ 4 = 3
dividend ÷  divisor = quotient

Factors
Factors are numbers that divide exactly into another number.
The factors of 12, for example, are 1, 2, 3, 4, 6 and 12.

Multiples
Multiples are extended times tables
The multiples of 2 are all the numbers in the 2 times table:
2, 4, 6, 8, 10, ...

Number Operations

                  Symbol.         Some Words/phrases

                       +                 add, sum, plus, total, more than, increased by

                       -           subtract, difference, minus, r less than, decreased

                       x           multiply, product, times 

                     /, ÷                divide, quotient


Order of Operations

          First Order.         :  (  )       Bracket                            B           

          Second Order     :  ÷ X     Multiplication, Division     DM

          Third Order         :  +  -     Addition, Subtraction       AS


FRACTION
Adding and Subtracting Like Fractions
Add or subtract the numerators
Do not add/subtract the denominator (it indicates the total portion)

Adding and subtracting Unlike Fractions 
Method
Step1: Change ALL DENOMINATOTORS to SAME VALUE (equivalent fractions)
Step2Add or subtract the NUMERATOR

Division Of Fractions
                           a     ÷    c
                           b           d             
                        = a     x    d
                           b           c              

DECIMALS
In the number 17.3, the point separates 17 from the 3. 
3 is in the tenth position. 
=> 3 of tenths = 3 of 1/10 = 3/10 
As a fraction, 17.3 = 17 3/10 

Decimal Numbers Multiply By 10s, 100s, 1000s
When a decimal number is MULTIPLY by 10, the decimal value shifts by ONE
PLACE to the RIGHT.

MEASUREMENT
Length
CONVERTING KM/M/CM/MM 
1 km = 1000 m
1 m = 100cm,
1 cm = 10 mm

Mass

CONVERTING Kilogram(kg) and Gram(g)

                                 1 kg = 1000 g

                                kg( / )--->g ( x )           

To convert kg to g, multiply the value by 1000 

To convert g to kg, divide the value by 1000 

Time

Commonly Used Terms



SHAPES
Rectangle and Square
Triangle

Perimeter adding the three sides
Area of Triangle = ½ x Base x Height
Circle
Angles
Lines

TYPE OF TRIANGLE ANGLES



OTHER ANGLES FORMULAE



QUADRILATERALS

<<< tri ~ 3 , quad ~ 4, cir ~ round >>>

STATISTICS

Drawing and Understanding Graph

Same set of Data in TABLE FORM:

 

Fruit

Numbers

Apple

  1

Pear

  2

Orange

  2

Banana

  3

Total

10

  

 

 

 

 

 

 

Average
Formula
       Average = Total Amount / Value 
                         Count of shares/items            


RATIO

Ratio compares two or more quantities.


            Symbol of ratio is    :     


Ratio of quantity A to quantity B s written as                                                                                                    

                  A : B                                                                                        

** Ratio has no unit of measure


Ratio and Fractions

A fraction is a part of a whole.


PERCENTAGE
"Percent % " means 
"per 100"   or  'out of 100'  or  ‘per 100 of the total value’
     -> the first quantity usually represents a part of, or a change in, the second quantity(the whole).
“per 100” => 
            60% = 60 / 100 
            25% = 25 / 100
Percent Formula: 
                        Percent = (Required) Value   x 100%
                                             Total Value
GST Formula:
                         GST = Amount x GST rate
                                                       100

SPEED

   Distance(D) = Speed (S) x Time (T)
            Speed = Distance / Time
              Time = Distance / Speed