1, 2, 3, 4, 5, 6, 7, 8, Or 9?

Riddle: I am a single digit number. When you add myself to me, you will get the answer to me by the addition symbol sideways, turned up-side-down. What number am I?

Answer: 9, or nine.

Source: https://www.riddles.com/6716

I am a single digit number. When you add myself to me, you will get the answer to me by the addition symbol sideways, turned up-side-down. What number am I? — 1, 2, 3, 4, 5, 6, 7, 8, or 9? by Chert v1.

Riddle: I am a single digit number. When you add myself to me, you will get the answer to me by the addition symbol sideways, turned up-side-down. What number am I? Answer: 9, or nine. — by Chert v2.