Premium Essay

Rounding to Decimal Places

If the next number is below 5, round down by leaving thr previous digit untouched.

Round 15.283 correct to 2 decimal places.

The answer is 15.28

If the next number is 5 or more, round up

Round 3.728 correct to 2 decimal places.

The answer is 3.73

Rounding to significant figures

For numbers between 0 and 1, start counting the significant figures from the first non-zero digit.

Round 0.007851 correct to 2 significant figures.

The answer is 0.0079

For numbers larger than 1, start counting the significant figures from the first digit.

Round 583 200 correct to 2 significant figures.

The answer is 580 000

Scientific notation.

13450700 in scientific notation is 1.34507 10

0.00125 in scientific notation is 1.25 10

7

3

Addition

Sum

Subtraction

Difference

Multiplication

*

: /

Product

Division

Quotient

Numbers

Real Numbers

Rational Numbers

Irrational Numbers

Definition of a rational number.

are not rational.

They are non-terminating & non-recurring decimals.

A number is rational if it can be expressed as a fraction in p the form q ,where p & q have no common factor and q 0.

Examples

2 8

Fractions, e.g. 3 , 17

Integers, e.g. 2 , 3, 15

Terminating decimals, e.g. 0.3562

Recurring decimals, e.g. 0.4 , 0.23, 0.17

Examples

, e.

Surds, e.g. 2 , 3 5 .

Transcendental numbers, e.g.

0.100100010000100....

Recurring decimals.

Example

Express 0.4 as a fraction.

Let x 0.4

10x 4.4

9x 4

4

x

9

Example

Express 0.13 as a fraction.

Let x 0.13

10x 1.3

100x 13.3

90x 12

12 2 x 90 15

Example

Express 0.23 as a fraction.

Let x 0.23

100x 23.23

99x 23

23 x 99

Subtraction

1.5371

3.2856

2. 2 51 5

3.2856

1.5371

1.74 8