To how many significant figures should each answer be rounded?
Equation:
A: ( 6.626 x 10^− 34 J * s ) ( 2.9979 x 10^8 m / s ) / 4.630 x 10^− 7 m = 4.290299222462 x 10^− 19 J ( unrounded )
1. After rounding, the answer to equation A should have .

After rounding, the answer to equation A should have  

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.

Rules for significant figures:

Digits from 1 to 9 are always significant and have infinite number of significant figures.

All non-zero numbers are always significant.

All zero’s between integers are always significant.

All zero’s preceding the first integers are never significant.

All zero’s after the decimal point are always significant.

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

In this problem, 6.626 has 4 significant figures, 4.630 has 4 significant figures and 2.9979 has 5 significant digits thus product will have the least number of significant figures which is 4. So, the answer will be in 4 significant figures. Thus the answer is

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