# All of these numbers have 3 significant figures right?

## Main Question or Discussion Point

12.5
100.00
105
2.5 x 10^3

All of these numbers have 3 significant figures right?

No, 12.5 and 105 have three significant figures. Look at the other two again

mgb_phys
Homework Helper
The last one is two sf, three would be 2.50 x10^3

105 is 3sig fig

The last one is two sf, three would be 2.50 x10^3

105 is 3sig fig
I caught that shortly after, thank you.

@pzona- Doesn't 100.00 only have two significant figures, the 1 and the two zeros after the decimal point?

symbolipoint
Homework Helper
Gold Member
I caught that shortly after, thank you.

@pzona- Doesn't 100.00 only have two significant figures, the 1 and the two zeros after the decimal point?
100.00 is written to indicate significance to the hundredths place. The number has five significant figures. (from locations of places Hundreds to Hundredths).

The way I learned sig figs, there were 3 main rules.

1. Zeros between nonzero digits are always significant (1001, 304)
2. Zeros at the beginning of a number are never significant (0.001, 0.026)
3. Zeros at the end of a number are significant if the number contains a decimal point (e.g. 100.00)

These are pretty easy to remember, and I still find myself going through them in my head every time I need to count significant figures. Hopefully this helps.