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### Course: Grade 8 math (FL B.E.S.T.)>Unit 1

Lesson 10: Significant figures

# Intro to significant figures

Significant figures are the number of digits in a value, often a measurement, that contribute to the degree of accuracy of the value. We start counting significant figures at the first non-zero digit. Calculate the number of significant figures for an assortment of numbers. Created by Sal Khan.

## Want to join the conversation?

• Can anyone help me because I got more confused watching the video...
• All non-zero digits are significant; 1, 2, 3, 4, 5, 6, 7, 8, and 9;

Zeros between non-zero digits are significant, like 705 and 80008;

Leading zeros are never significant, like in 0.03 or 0068;

Trailing zeros are significant ONLY if a decimal place is present; examples where the zeros are not significant include 100, 380; those that are include 38.00, 590.0, and 280.190;

I hope this helps! Realizes that the post was made 8 years ago Oh well
• What if the number is 0? Would that just be 0 significant figures?
• No. Alone zero is not considered as significant figure.
• At , Sal covers the number 370. and how many significant figures there are in it. I'm confused about why someone would put a decimal after a number and not put any numbers after it. What is the purpose of this? If the measurement is exactly 370 anyway, why can't the number be 370.0 instead?
• From what I understand, '370.' shows that the number is accurate up to the ones place (e.g. that it is 370 and not a rounded 373 or 368). It could actually represent 370.4, but '370.' is still a correct representation of 370.4 as '370.'is accurate up to the ones place and 370.4 rounded to the ones place is 370.

370 and 370.0 mathematically represent the same number but with significant figures, 370 is accurate up to the ones place and 370.0 is accurate up to the tenths place. Referencing the previously mentioned example, 370.4 can be accurately represented as '370.', but not 370.0.
Hope that helps!
• I don't really get it is it just like : 00.30000 mean it's has 4 significant figures?
• 00.30000 has five significant figures: the 3 and the four zeros behind
• Why are the trailing zeros in a decimal number significant?
• Because they indicate that you measured that value to a higher degree of precision. If I measure something as exactly 100 millimeters and record it as 0.100 meters, that represents something different than saying 0.1 meters since in the later case it may of actually been 0.12m or 0.9m and I just rounded it off. By adding the extra 0s you know that the only rounding would have been to the nearest mm.
• If we have a number like 14.03 and we need to round it to one significant digit, how would we do this?
• Anthony is incorrect. If you want one significant digit, then the 4 is not significant either, and you just write down "10".
• i thought all digits were significant....
Protest for the rights of 0's!
• How would we do this for a number like .3 repeating? Is the number of significant digits infinite?