Yes, you can go to a bank and request to exchange twenty dollar bills for 100 dollar bills [1]. This type of transaction is known as currency exchange or bill swapping, and most banks should be able to accommodate this request, depending on their available cash denominations.

Here are some key points to keep in mind when exchanging bills at a bank:

1. Availability: Not all banks may have a sufficient supply of 100 dollar bills on hand, so it's advisable to call ahead or visit a branch that is likely to have the desired denomination available.

2. Identification: When exchanging bills, it's important to have a valid form of identification, such as a driver's license or passport, to complete the transaction [3].

3. Condition of Bills: Banks generally accept bills that are in relatively good condition, with no significant tears or missing parts. They may refuse to exchange bills that are torn, heavily damaged, or counterfeit [3].

4. Fees: Banks typically do not charge fees for exchanging bills, as this service is part of their regular banking operations [3].

5. Account Requirement: In most cases, you do not need to have an account at the bank to exchange bills. However, it's always a good idea to check with the specific bank beforehand to confirm their policies.

Learn more:

1. Can you go to any bank and trade twenty dollar bills ... - Quora
2. united states - Where can I exchange small bills for larger denominations? - Personal Finance & Money Stack Exchange
3. Where And How To Exchange Old 100-Dollar Bills - Chronicle Collectibles