# Biojjb

In:

Submitted By lanann
Words 8924
Pages 36
Basics

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.
If the next number is 5 or more, round up
Round 3.728 correct to 2 decimal places.

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.
For numbers larger than 1, start counting the significant figures from the first digit.
Round 583 200 correct to 2 significant figures.

Scientific notation.
13450700 in scientific notation is 1.34507  10
0.00125 in scientific notation is 1.25  10

7

3

 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