Question

how many significant figures are in the following measurements. 0.006 070 degree C and 1.305 20 MHz

Answer 1

Could you rewrite the question so it's more clear? Is that 4 different values or ?

Answer 2

The question is pretty clear. Digits are simply in groups of three.

The rule is to ignore the zeroes before the first non-zero digit, and to take into account all other digits (zeroes included).

Answer 3

I guess I didn't see that it could be in groups of 3...we don't write digits that way in the U.S.

Answer 4

For the record, trailing zeroes are only significant after the decimal point

Answer 5

Yes you can, when numbers have a large number of digits.

Have a look for instance at pages 19 or 34 of the NIST brochure about the SI.
Actual rules are in paragraph 5.3.4 on page 42.
http://physics.nist.gov/Pubs/SP330/sp330.pdf

Answer 6

I know you can write them that way....but it's still not very common in the U.S. A comma is a lot more common as a group separator.

Answer 7

"For the record, trailing zeroes are only significant after the decimal point"

This statement is correct in 'normal' instances, but that is nonetheless inaccurate.
This rule would give 6 sf to the first quantity, but it has only 4.

0.006 070 °C = 6.070x10^(-3) °C (4 sf)

Answer 8

I don't see how anyone could interpret the left quantity as having 6 sigfigs given the rules:

0.006070

All of the zeroes before the 6 are *leading* digits and are therefore insignificant (regardless of a decimal point). Trailing digits are those that following the last non-zero digit...the only trailing digit in the above is the last 0.

Answer 9

Agreed, the 'trailing' zeroes are unambiguous, but no reference to the decimal point is necessary then.