Even though we are well into the course dumbledore notices some of the students are still having trouble with significant figures. let’s review them once more: how many significant figures does the result of the following calculation have? (3.478-2.31)*(4.428-3.56)?
a) 1
b) 2
c) 3
d) 4
e) 5 2.

B) 2

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.

The rule apply for the addition and subtraction is :

The least precise number present after the decimal point determines the number of significant figures in the answer.

(3.478-2.31) = 1.168 ≅ 1.17 (Rounded to least decimal digit)

(4.428-3.56) = 0.868 ≅ 0.87 (Rounded to least decimal digit)

So,

1.17 * 0.87 = 1.0  (Rounded to least significant)

Answer - two significant digits