How many of the following numbers contain 3 significant figures?
0) 408 9.040 0.0 400 9.05 × 10²⁴

Question

How many of the following numbers contain 3 significant figures? 0)408 9.040 0.0 400 9.05 × 10²⁴ A)one B)two C)three D)four

Quizplus · Accepted Answer

Remember that significant figures are the number of digits in a number that are reliable and meaningful. 
In order to determine how many numbers have 3 significant figures here we have to count the digits starting with the first non-zero digit. 
So,
408 has 3 significant figures
9.040 has 4 significant figures
0.0400 has 3 significant figures
9.05 × 10^11 has 3 significant figures
Therefore, there are 3 numbers with 3 significant figures: 408, 0.0400, and 9.05 × 10^11.

How Many of the Following Numbers Contain 3 Significant Figures