Question

A classmate finds that it takes 1.090 seconds for a tossed ball to touch ground. How many significant figures are in this measurement?

A) 4
B) 3
C) 2
D) 1

Answer 1

B: 3

The reason for this is that trailing zeroes are not counted as significant figures, so any zeroes after the final digit are not to be counted. in this case, the 9 in the hundredths place value would be the final number you would count, and you would chop off the trailing zero, leaving it as 1.09.

Answer 2

Option A: 4.

In a number, to determine the number of significant figures following 3 rules are used:

(1) The digits which are non-zero are always significant.

(2) Any zeros between two digits which are non-zero are significant.

(3) In the decimal portion, trailing zeros are significant.

The number is 1.090, it has two non-zero digits, 1 zero in between two non-zero digit and one trailing zero thus, all of them are significant figures.

Therefore, it has 4 significant figures (underlined): 1.090