Answer:
I would say E and F
Step-by-step explanation:
E: I assume this means writing the answer down and giving it a label, which is what you would do after solving a problem.
F: Double checking your answer is a good thing to do after solving it.
B: it could also be B, but usually you name variables before you find what they are so I personally don't think it is.
2 x 10 to the -6th power is .000002.
11 and 51
1 technically isn't a prime since a prime can only be divided by two things (itself and 1) and 1 can only be divided by 1.
21 can be divided by 1, 3, 7, and 21 so it is not prime.
Hope this helps!
A and F
