What is a significant figure in math?

Answer 1

It's a number of digits which you have to take in count when you have to round a number (physical value such as speed, acceleration and so on).

e.g. if you have the number 0.0000067 the signifigant figures are 67; zeros don't matter, unless they are between two actual numbers like in 405000 the signifigant figures are 405

Answer 2

Perhaps you mean significant digits or figures? In that case it is the resolution of a calculation. How many decimal places the answer contains.

For example:

You are asked to calculate the circumference of a circle with diameter 2.4 meters.

The input data is given with a resolution of two figures, two significant digits; so the answer cannot have more than two digits even though you might use a value of pi that has many more significant figures (3.1415926535897932384626433832795) your answer should be

7.5 meters

If the input was a diameter of 2.400 meters (four significant digits - measured to the closest millimeter) the answer should be:

7.540 (the last zero is significant!)

If the diameter had been measured to the nearest micrometer (difficult but not impossible) and given as 2.400000 meters (significant trailing zeros) the circumference should be calculated as:

7.539822 seven significant digits.

Using an electronic calculator often gives a false sense of accuracy because the answer always contains a large number of digits but if the input data is not all that accurate you have an answer in the output that has unreasonably accuracy (resolution).

Answer 3

Each measurement is considered to have a certain number of what are called significant digits or significant figures ( aka sig figs or sig.digs ) . Rules for Identifying the Number of Significant Digits in a Number Rules 1)Any nonzero (digits from 1 to 9 ) digits are significant . 2)Any zeroes found between two significant digits are significant . 3)Any zeroes that are found to the right of both a significant digit and a decimal place are significant . Examples from the Rules Above According To Each Rule 1)Number 942 , with three nonzero digits , shows 3 significant digits 2)Number 50003 , with 2 nonzero digits and 3 zeroes between and significant digits , shows 5 significant digits . 3)Number 75.00 , with 2 nonzero digits and 2 zeroes that are to the right of both a significant digit and a decimal shows 4 significant digits . Always consider each rule and try memorizing them ,Practice and Memorize