Step-by-step explanation:
A. When dealing with large numbers, sometimes it's easier to write them in a form of exponents of number ten. The value of the exponent shows how many times we multiply 10 by itself. That means that 10^3 is 10•10•10 or that 10^6 is 10•10•10•10•10•10.
So, when finding how many times on number is greater then the other, we need to divide them. We divide 8x10^6 by 2x10^5. It is done by dividing the numbers and subtracting the exponents; 8/2=4 and 10^6/10^5 is 10^6-5=10^1. So the correct answer is 4x10^1 which is 4x10, and that is 40.
B. Now, we have a total number of coins (2.25x10^5), and diametar of a coin (19mm = 19x10^-6km). Our task is to calculate the distance across which the coiks laid side-by-side would expand. We can find this by multiplying the number of coins with a diametar of single penny, 2.25x10^5•19x10^-6. Multiplying is done by multiplying the numbers (2.25x19=42.75) and adding the exponents (5+(-6)=5-6=-1). So, the distance is 42.75x10^-1km, which equals to 4.275 km. Obviously, this is less then the stated 5 km given in the text, so the reportet's statement is false.
