Question 83875
The area of a circle is {{{pi*r^2}}}
If you are tol to round your answer to the nearest whole 
number, then say your answer is 4.499. This is closer to 4
than it is to 5, so your answer is 4. Say your answer is
4.501. This is closer to 5 than to 4, so your answer is 5.
You have to know what value to use for pi, too. It wmight make
a difference in your answer. 
3.141 is 3-place accuracy
3.1415 is 4-place accuracy
3.14159 is 5-place accuracy
You should be told how many decimal places to use on the quiz.
Suppose the radius of a circle is a really big number.
Suppose {{{r = 5641896}}} inches, then
{{{A = pi*5641^2}}}
Here, the fewer decimal places you use for pi, the more accuracy you're
going to lose in your answer. I'll try examples, rounding to the nearest
whole number
{{{A[1] = 3.141 *31820881}}}
{{{A[1] = 99949387}}}
{{{A[2] = 3.1415 * 31820881}}}
{{{A[2] = 99965298}}}
I'm getting better and better accuracy with more accurate values of pi.
This is only true because r is a large number. I need just as many decimal
places for pi as there are digits in r. After that I won't get
better accuracy rounded to the nearest whole number.