It depends. If you are saying "The store is open 24 hours." then NO. But if you are saying "It is a 24-hour store." then YES you can. It is often hyphenated when used as an adjective preceding a noun. There is no definitive rule, but it is quite common to hyphenate 24-hour in these cases.
Yes it should be hyphenated.
Yes, it should be hyphenated.
because
Yes it should be hyphenated.
yes check-up should be hyphenated
It should be hyphenated.
"Field" is not hyphenated.
no, it shouldn't be hyphenated.
Yes it should be hyphenated.
No it shouldn't be hyphenated.
Yes it should be hyphenated.
Yes it should be hyphenated.