You measure two quantities as A = 1.0 m ± 0.2 m, B = 2.0 m ± 0.2 m. We should report correct value for as:

Let

Let be the error in X.

From error analysis we know that,

(For the formula part refer to

NCERT class 11 part 1 unit

and measurement chapter)

Putting the known values we get,

In dimensional analysis, in multiplication the answer is rounded off to the same number of significant figures as possessed by the least precise term used in the calculation. Here 0.1 has least precision and has 1 significant figure. Therefore,

(By rounding off to one significant figure)