With a number of 328×41 and coming up with a answer of nearly 5,000 is not reasonable because just estimating it 300×10 is 3,000 so times that by 4 is 12,000.
Grab a sheet of paper and follow along, write 328 x 41 and put 328 on top of 41. multiply 8 x 1 multiply 2 x 1 multiply 3 x 1 multiply 8 x 4 which is 32 multiply 2 x 4 which is 8 multiply 3 x 4 which is 12 bring down the carry digit of 1 add 328 + 13120 which is 13448 or multiply 328 x 41 and u get 13448
The answer is not reasonable because its not the correct solution.
The surface area of a sphere is where r is the radius; The circumference is so that using this value we can evaluate the surface area of 1 ball as: For 100 ball you get:
where r is the radius;
so that 
using this value we can evaluate the surface area of 1 ball as:
