Significant Figures in Calculations:
In Order to Correct the Number of Significant Figures in a Calculation:
1.). Â First, you would, Â Add all the digits: Â
(Example: 1405.2 Â + Â Â 9.77 Â Â + Â Â 4.32 Â Â = Â Â Â 1419.29)
2.). Â Then, You would Round the final value to the Least Number of Significant Figures. Â
(In Example, it would look like this: Â 1420).
Therefore, The least number of significant figures  in the Example, is 3.
(However, In the Example, the number 1420,) Â Â The "0" isn't a significant figure.
Hope that helps!!!! Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â : ) Â Â
You didn't write the significant numbers in, So, I just gave you an Example, of how would actually solve Significant Figures Calculation!