A company prints contest codes on its fun-size bags of candy. Each 6-character code consists of the letter A
followed by the letter H followed by 4 of the digits 0
through 9. The digits may repeat. Which of the
following expressions gives the number of different
6-character codes that are possible?
F. 1(1)(10)(10)(10) (10)
G. 2(1)(10)(9)(8)(7)
H. 2(1)(10)(10)(10)(10)
J. 2(2)(10)(9)(8)(7)
K. 2(2)(10)(10)(10)(10)

Using the Fundamental Counting Theorem, it is found that the expression that  gives the number of different  6 -character codes that are possible is:

F. 1(1)(10)(10)(10) (10)

Fundamental counting theorem:

States that if there are n things, each with ways to be done, each thing independent of the other, the number of ways they can be done is:

In this problem:

Hence:

And option F is correct.

To learn more about the Fundamental Counting Theorem, you can take a look at link

inverse operation of addition

the answer to your question is b.