Question

The accuracy of measurement also lies in the way the result is expressed. The number of digits to which a value is to be expressed is one digit more than number of sure numbers. Rules do exist to deal with number of digits after an operation is carried out on the given values. The error can be minimised by many trials and using the correct methods and instruments.
If the length and breadth are measured as $4.234$ and $1.05$ m, the area of the rectangle is

• A. $4.4457m^2$
• B. $4.45m^2$
• C. $4.446m^2$
• D. $0.4446m^2$

Answer 1

The correct option is B $4.45m^2$

Area $=$ $lb$ $=4.234\times 1.05$

$=4.4457$

Now on multiplication of two decimal type number having significant figures. After multiplication the result must contain the same no. of significant figure as the number having least significant figure.

Here,

Least significant figures $=3$

SO

Area $=4.45$ $m^2$ [After rounding off].

Hence the correct option is B.