Anytime we're asked to count how many significant figures are in a given number, we follow the same set of rules:

- All non-zero digits are always significant.
- Zeroes between non-zero digits are always significant.
- Leading zeroes are never significant.
- Trailing zeroes are only significant when the number contains a decimal point.
- The last significant figure in a number is the last digit that is known with certainty.

(a) The notation 78.9 ± 0.2 means that the true value of the number is somewhere between 78.9-2 and 78.9+2. Rounding to two digits, *both 78.7 and 79.1 become 79*. That means the 1's place is the last certain digit, so this number has __two significant figures__.

How many significant figures are in the following numbers? (a) 78.9 ± 0.2 (b) 3.788 × 10^{9} (c) 2.06 × 10^{26} (d) 0.0053

Frequently Asked Questions

What scientific concept do you need to know in order to solve this problem?

Our tutors have indicated that to solve this problem you will need to apply the Uncertainty concept. If you need more Uncertainty practice, you can also practice Uncertainty practice problems.

What professor is this problem relevant for?

Based on our data, we think this problem is relevant for Professor Voronine's class at USF.