Question

What is 48,100,000,000,000 in scientific notation?

Answer 1

4.81 x 10^13 

But to reduce significant figures, 

5.0 x 10^13

Answer 2

Scientific notation is
$x*10^b$ where 1≤x<10 and b is an integer

b is how many spaces you had to move the decimal to the left in the original number to obtain x

so
48,100,000,000,000
to
4.8100000000000
the decimal was moved 13 spaces
so b=13
a=4.81


in scientific notation, 48,100,000,000,000 is $4.81*10^{13}$