What it means
ついでに means “while you are at it” or “taking the opportunity.” It shows that the action after ついでに is a secondary action performed conveniently during or immediately after another action. It commonly follows a noun with の or a verb in the dictionary form or past form. The main action usually creates the opportunity for the additional action.
Usage note
The action after ついでに should normally be a useful or natural extra action, rather than an equally important action in a simple sequence. The politeness of ついでに itself does not change; use a polite form in the main predicate when speaking politely.
How to use it
私は出張のついでに、京都の支店を訪ねます。
While on a business trip, I visit the Kyoto branch.
私は駅へ行くついでに、郵便局で荷物を出します。
While going to the station, I mail a package at the post office.
私は図書館で本を借りたついでに、大学の食堂で昼食を食べます。
After borrowing a book at the library, I eat lunch at the university cafeteria.
私は出張のついでに、京都の支店を訪ねる。
While on a business trip, I visit the Kyoto branch.
私は駅へ行くついでに、郵便局で荷物を出す。
While going to the station, I mail a package at the post office.
私は図書館で本を借りたついでに、大学の食堂で昼食を食べる。
After borrowing a book at the library, I eat lunch at the university cafeteria.
Example sentences
市役所へ行ったついでに、近くの図書館で借りた本を返しました。
Taking the opportunity when I went to city hall, I returned the book I had borrowed at the nearby library.
スーパーで買い物をするついでに、郵便局で荷物を送りました。
While shopping at the supermarket, I took the opportunity to send a package at the post office.
病院で診察を