# Problem: How many significant figures are in the following numbers? (a) 78.9 ± 0.2 (b) 3.788 × 109 (c) 2.06 × 1026 (d) 0.0053

###### FREE Expert Solution

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.

82% (324 ratings) ###### Problem Details

How many significant figures are in the following numbers? (a) 78.9 ± 0.2 (b) 3.788 × 109 (c) 2.06 × 1026 (d) 0.0053