Both numbers in the numerator have 3 significant digits.
The denominator has 4 significant digits.  

Just as a chain is no stronger than its weakest link, no answer 
can have more significant digits than the least number of 
significant digits in any number used to calculate it. So
the answer must be rounded to 3 significant digits. 





1975.777063

In scientific notation:

1.975777069 × 10³

But we must round the decimal part off to
three significant digits:

1.98 × 10³

Edwin