how does she ask for his number??

so my best friend works with this guy and has developed this huge crush on him, and he seems to like her too. the issue is she works register and he’s a stocking boy, so it’s not like she can just say “hey can i have ur number in case we need to cover shifts or something?” since they have different jobs, so how can she get his number without saying she likes him? (otherwise work will be awkward if he ends up not liking her) i know it’s dumb, but please help