Question

what do you mean by significant figures? state the rules for deciding significant figures​

Answer 1

The number or figures of the digits that contribute to the accuracy of the value is known as significant figures.

The rules for knowing the significant figures are -

1. The digits which are non zero are considered as significant.

2. The zeroes which are present between the digits that are not zero are significant.

3. Zeroes which are present at the left side of the 1st digit that is not zero are not regarded as significant.

4. The zeroes which are present at the right area of the decimal are significant.

5. Zeroes located at the left part of point of decimal may or may not be regarded as significant.

Answer 2

Explanation:

There are three rules on determining how many significant figures are in a number:

Non-zero digits are always significant.

Any zeros between two significant digits are significant.

A final zero or trailing zeros in the decimal portion ONLY are significant.

Focus on these rules and learn them well. They will be used extensively throughout the remainder of this course. You would be well advised to do as many problems as needed to nail the concept of significant figures down tight and then do some more, just to be sure.

Please remember that, in science, all numbers are based upon measurements (except for a very few that are defined). Since all measurements are uncertain, we must only use those numbers that are meaningful. A common ruler cannot measure something to be 22.4072643 cm long. Not all of the digits have meaning (significance) and, therefore, should not be written down. In science, only the numbers that have significance (derived from measurement) are written.

Rule 1: Non-zero digits are always significant.

Hopefully, this rule seems rather obvious. If you measure something and the device you use (ruler, thermometer, triple-beam balance, etc.) returns a number to you, then you have made a measurement decision and that ACT of measuring gives significance to that particular numeral (or digit) in the overall value you obtain.

Hence a number like 26.38 would have four significant figures and 7.94 would have three. The problem comes with numbers like 0.00980 or 28.09.

Rule 2: Any zeros between two significant digits are significant.

Suppose you had a number like 406. By the first rule, the 4 and the 6 are significant. However, to make a measurement decision on the 4 (in the hundred's place) and the 6 (in the unit's place), you HAD to have made a decision on the ten's place. The measurement scale for this number would have hundreds and tens marked with an estimation made in the unit's place. Like this:

Rule 3: A final zero or trailing zeros in the decimal portion ONLY are significant.

This rule causes the most difficulty with students. Here are two examples of this rule with the zeros this rule affects in boldface:

0.00500

0.03040

Here are two more examples where the significant zeros are in boldface:

2.30 x 10�5

4.500 x 1012