## Sunday, April 12, 2009

### [Mathematic Form 4] Get The Right Figure

In scientific or technical studies, very large or very small numbers are used sometimes.

Eg:
The speed of light is approximately 300,000,000 m/s.

The mass of one oxygen atom is approximately 0.000000000000000000027 g.

That's quite a number of zeros, isn't it? Imagine the amount of space they would take up in your exercise books.

To manage these extremely large or small numbers more easily, we use significant figures and the standard form.

The accuracy level of a measurement in scientific work is indicated by the number of significant figures it has.

Here are some rules to follow when dealing with significant figures;

Rule 1: All non-zero digits are significant.
Eg:
6.78 has 3 significant figures
97.122 has 5 significant figures

Rule 2: Zeros between non-zero digits are significant figures.
Eg:
1,007 (4 significant figure)
3.0002 (5 significant figure)

Rule 3: A zero after the decimal point of a decimal number is a significant figure.
Eg:
6.0 (2 significant figure)
18.00 (4 significant figure)

Rule 4: In a decimal, zeros before the first non-zero digit are not significant.
Eg:
0.00865 (3 significant figure) [the first three zeros are not significant]
0.06 (1 significant figure) [the first two zeros are not significant]

Rule 5: In a whole number, zeros after the last non-zero digit may or may not be significant, depending on the level of accuracy specified.
Eg:
74,000 has 2 significant figure when rounded off to the nearest thousand.
74,000 has 3 significant figure when rounded off to the nearest hundred.