The Frog And The Well

Riddle: A frog fell into a 12-foot-deep well. He could jump 3 feet, but every time he jumped 3 feet, he fell back 2 feet. How many times did he have to jump to get out of the well?

Answer: 10. On the tenth jump he cleared the edge of the well and thus did not fall back two feet.

Source: https://www.riddles.com/index.php/1374

A frog fell into a 12-foot-deep well. He could jump 3 feet, but every time he jumped 3 feet, he fell back 2 feet. How many times did he have to jump to get out of the well? — The Frog and the Well by Anonymous Riddle