Which is correct- maria's number or marias' number?

Answer 1

Maria's number is correct. Maria doesn't have an "S" at the end, such as Chris, so you place the apostrophe before the "S"

Examples:

Maria's Number

Chris' Number (Not Chris's or Chri's Number)

Answer 2

Oh, dude, it's actually neither! The correct way to show possession for Maria's number is "Maria's number." You don't need that extra apostrophe at the end. So, next time you're texting Maria, make sure you get that punctuation right!