Significant Numbers

[Yuzhe Yuan]

How many significant numbers do 200 , 200. , 200.00 , and 2.0x10² have, respectively?

[Ivan_Tang_2G]

200 = 1sf
200. = 3sf
200.00 = 5sf
2.0*10^2 = 2sf

[Jonathan Alterman 1C]

Hi!
200 would have only 1 significant figure because zeroes don't count if there are no digits (1-9) after them without a decimal.
200. would have 3 significant figures because the decimal makes all digits to the left significant.
200.00 would have 5 sig. figs. because all zeroes to the left and right would count in addition to the digit if there is a decimal.
2.0E10^2 would have 2 sig. figs. because with scientific notation and the decimal makes both numbers, left and right of the decimal, would be significant.

[Ryan Lafferty 1L]

200 has 1 significant figure.
200. has 3 significant figures.
200.00 has 5 significant figures.
2.0x10^2 has 2 significant figures.

[Sanjana Sivakumar 2E]

Hey!

I see that everyone has already answered your questions, so I won't repeat it. However, I would just like to add some basic rules to remember when trying to find how many significant figures there are.

- Any non-zero number is significant. Ex: 253 has 3 sig. figs.
- Any zeros that are between numbers is significant. Ex: 101 has 3 sig. figs.
- Leading zero are not significant. Ex: 0.03 has 1 sig. fig.
- Zeros to the right of the decimal are significant. Ex: 13.00 has 4 sig. figs.
- Zeros in a whole number with a decimal is significant. Ex: 230. has 3 sig. figs. while 230 only has 2

- In Scientific Notation, only the number you are multiplying is significant if the rules above apply.
Ex: 3.1415 x 10²¹ has 5 sig. figs (the 3.1415 part).

Hope this helps for future exercises!

[Jillian Sarquiz- 2B]

200 has 1 sf
200. has 3 sf
200.00 has 5 sf
2.0x10^2 has 2 sf

Dr. Lavelle has a great review of significant figures on his website under "Everything you want to know about Significant Figures"