How to say "in a split second" or "really quickly" in Japanese

Do you know how to say "in a split second" or "really quickly" in Japanese?

Let's try a Japanese language quiz!

（　　　）という間（ま）に大きくなったね！

Meaning : You've grown up so fast.

Choose an answer from from 1～4.

①かっ
②へっ
③あっえ）
④おっ

答えは・・・The answer is・・・

③あっ

Meaning

あっという間（ま）
before I knew it/ in a split second/ in the time it takes to say "ah!"

◆ 例文：Example Sentences

あっという間に大きくなったね！
You grew up before I knew it! You've grown up so fast!

あっという間にもう１月も終わりです。
It's already the end of January! January ended before I knew it!

Did you get the quiz right?

Cherish each and every day！
Good luck with your studies!