Question

The answer to the problem: (2.1x103) x (4x105) = _____, written to the correct number of significant digits and in scientific notation is:

!! Carat denotes to the power. Example: 10^4 is 104 !!

Answer 1

Answer:  The answer is $8.4\times 10^8$

Explanation:

Significant figures : The figures in a number which express the value -the magnitude of a quantity to a specific degree of accuracy is known as significant digits.

The rule apply for the multiplication and division is :

The least number of significant figures in any number of the problem determines the number of significant figures in the answer.

Thus for product of  $(2.1\times 10^3)\times (4\times 10^5)$

In this problem, 2.1has 2 significant figures and 4 is an exact number with infinite significant digits thus product will have the least number of significant figures which is 2. So, the answer will be in 2 significant figures.

Therefore, the answer is $8.4\times 10^8$