How would you round off .002353 to two significant figure ?

The answer is 0.024.

Let's round decimal by decimal until we get two significant figures.
When the successor number is smaller than 5 then the predecessor number remains the same.
When the successor number is greater than 5 then the predecessor number rounds to the first greater number.
If the successor number is 5 then the even predecessor number remains the same and the odd predecessor number rounds to the first greater number.
0.002353 ≈ 0.00235
0.00235 ≈ 0.0024

Now, we have two significant figures: 2 and 4