Question

http://prntscr.com/hbfgs2

Answer 1

as a hint: adding two integers will always produce another integer

Answer 2

so not closed?

Answer 3

closed

Answer 4

(this is the definition of closure - the operation will always produce another type of number in that set)

Answer 5

but its division?

Answer 6

oh whoops

Answer 7

yeah you're right ;_: not closed