30.900 has 5 significant figures.
In 30900 there are [at least] three significant figures.
3.
There are three.
There is one significant digit in the number 10, as written.
30.900 has 5 significant figures.
In 30900 there are [at least] three significant figures.
3.
There are three.
There is one significant digit in the number 10, as written.
One of them.
The number whose farthest right significant digit determines it. Whatever place that digit is in is the last significant digit in the sum. For example: 433 + 150 + 3.67 + 8000 = 8586.67, but in sig figs this is only 9000, as the thousands digit is the lowest digit that can be represented.
Five. Count from the first nonzero digit to the last nonzero digit.
The number 02 has one significant figure because a leading zero is not significant. So the significant figure is the digit 2.
Three significant figures. The two zeroes after the digit 5 are irrelevant.
5. Count the number of digits from the first non-zero digit to the last non-zero digit.
The number 0.3 has one significant figure. The digit '3' is the only non-zero digit and is considered significant, while the leading zero before the decimal point does not count as a significant figure.