B121

Chapter 5

Working with Numbers

Number representationThousand Hundreds Tens Units

2563 2 5 6 3

Natural numbers: 1,2,3,4,5………Integers: Natural numbers are examples of integers or whole numbers: 0,1,2,3……Negative numbers: these are numbers with a value of less than zero: -1, -2, -3, -4

Working with numbers

Getting the order rightOrder of operation: BIDMASB : Brackets I : Indices (powers and roots) D: Division M: Multiplication A : Addition S : Subtraction

Using BIDMAS rule

a) 8 – 2 + 5 – 1

b) 5 + 12 ÷ 4

c) 4 x 5²

d) (5 – 3) x 4

Terms for calculation

SUM : the sum of two numbers is the result of adding them together.

Difference : subtracting one from the other.

Product : Multiplying two numbers.

Quotient : Dividing one by the other

Rounding Numbers

To round a numberLook at the digit immediately after where you want to round.

Round up if this digit is 5 or more, and down otherwise.

a) 0.0582 to three decimal places.

b) 7.05683 to one decimal places.

c) 2.3971 to two places.

Negative Numbers

Adding and subtracting negative numbers

Adding and subtracting negative numbers

Adding a Negative number is same as subtracting the corresponding positive number.

Subtracting a Negative number is same as adding the corresponding positive number.

Multiplying and Dividing Negative number

When Two numbers are multiplied or divided:

if the signs are different, then the answer is Negative.

If the signs are same, then the answer is positive.

Fraction

• A fraction is a number that describes the relationship between part of something and the whole.

• For ex. The disc is divided into 8 equal parts of which 5 are shaded. To express

this we write ⅝.

Top number is called numerator.

Bottom number is called denominator

Equivalent FractionsEach fraction can be written in many different, but equivalent forms.

To find equivalent fraction Multiply or Divide the

numerator and denominator by the same non-zero number.

Unit1: Starting Point

 

Unit1: Starting Point

Mathematical terms:

Sum : Adding numbers together

Difference: subtracting between two numbers

Product: is the result of multiplying them

Quotient: is the result of dividing numbers

a) Two numbers with sum 8 and product 15=?

b) Two numbers with difference 4 and quotient 2?

Unit1: Starting Point

 

Unit1: Starting Point2.4 Rounding numbers:

Decimal places:

When you make a measurement, it is sometimes helpful to round your answer.

Decimal places: are the positions of the digits to the right of the decimal point. 0.0582

- Round 0.0582 to three decimal places

The answer is = 0.058- Round 2.3971 to two decimal places

The answer is = 2.40- Round 0.00547 to three decimal places ??- Round 7.98 to one decimal place ??

Unit1: Starting Point

2.4 Rounding numbers:

Significant figures: Another way where a number should be rounded is looking at its significant number.

- Round 36.9572 to four significant figure:

36.96- Round 0.0198 to two significant figure:

0.020 - Round 23650 to two significant figure:

??

3. Negative numbers and fractions:

3.1 Negative numbers- Figure 10 at page 28 shows part of the number line,

with the positions of the integers marked. For example:

-2 + 5 = 3

-1- 4 = -5

-6 + 2 = - 4

2 – 7 = ?

5 – 7 – 2 = ?

3. Negative numbers and fractions:

 

3. Negative numbers and fractions:

3.2 Fractions:

Fractions are important in mathematics.

A fraction is a number that describes the relationship between part of something and the whole.

The top number is called numerator

The bottom number is called denominator

Fraction can be converted into decimal

3. Negative numbers and fractions:

 

3. Negative numbers and fractions: