# What is the number of significant digits in a integer with trailing 0's ?

## Main Question or Discussion Point

It seems that there is a possible ambiguity in the number of significant digits if there are trailing 0's, but no decimal point or overline or underline. Specifically, I am looking at the definition of the second, which the Halliday & Resnick book has listed as

9 192 631 770

So is this 9 or 10 digits? Should it be presumed that an integer with trailing 0's, but without the decimal point, overline or underline has those 0's as significant or not?

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Of course they are significant. Try taking them out - the number changes.

Doc Al
Mentor
It seems that there is a possible ambiguity in the number of significant digits if there are trailing 0's, but no decimal point or overline or underline. Specifically, I am looking at the definition of the second, which the Halliday & Resnick book has listed as

9 192 631 770

So is this 9 or 10 digits? Should it be presumed that an integer with trailing 0's, but without the decimal point, overline or underline has those 0's as significant or not?
In this particular case--with the definition of the second--that number is meant as an exact number.

But in general you'd be correct. A measured quantity written as that number is would have 10 digits, with only the first 9 being significant.