Answer: 3 significant digits
Step-by-step explanation:
When a number is written in scientific notation (representing the number using powers of base ten) it is expressed so that it contains a digit in the place of the units and all other digits after the decimal point, multiplied by the respective exponent.
Then, the significant figures (or significant digits) will be the digits that are before the power of ten.
For example, the number
has 4 significant figures.
Now, in the case of the number
it contains 3 significant figures.