Answer
a) 2
b) 4
Work Step by Step
a) 0.000054
Using the scientific notation, this number can be written as
5.4 $\times 10^{-5}$.
The zeros before the number are insignificant. In this case, after writing the number using scientific notation, it can be said that the number has 2 significant digits.
b) 3.001$\times 10^{5}$
Here, the number has 4 significant digits as the zeroes between 3 and 1 are significant.
