If you have one account: You'll find the account number in the upper right corner of page one of the statement.
If you have a credit card: You're account number is on your card and digital banking. See also, How do I find my credit card number (virtual card)?
If you have more than one account: We'll send a one statement with the details of each account.
See also: Why did I get one statement when I have multiple accounts with U.S. Bank?