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
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Addition
Sum
Subtraction
Difference
Multiplication
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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
