Question

The actual product of 4.327 and 2.8 is 12.1156. The correctly reported answer will be:
A. 12
B. 12.1
C. 12.12
D. 12.116

Answer 1

Hint: The significant figures after the decimal point tells us about the accuracy and precision about any value. After multiplying or dividing, the significant figures have to be rounded off to the lowest significant figures in the question.

Complete answer:
Significant figures in chemistry tell us the valuable digits in a particular mathematical operation. The addition, subtraction, multiplication, and division of significant figures is done as usual. But the rounding off of numbers is done with the minimum significant figure that the numbers being adding, subtracting, multiplying, or dividing contain.
So, the given product of the numbers, 4.327 and 2.8 which is 12.1156 have to be rounded up to the minimum significant figure of 2.8 value which is 2. Therefore the rounding off will give 12.
Hence, the correctly reported product is 12.

So, option A is correct.

Note: The values of significant figures depend on the rules of significant figures. Some of the rules are:
- All the digits that have no zero are significant. For example, 32 have 2 significant figures.
- The zeros that are written before non-zero digits are not significant. For example, 0.0047 have 2 significant figures.
- Zeros that are written between the non- zero digits are significant. For example, 4.009 have 4 significant figures.
- When any scientific notation is written, it is not significant.
- When the exact number of anything is written, it has an infinite number of significant figures. For example, 20 eggs have infinite significant figures.