## Calculator keys

*Difficulty level:*

A calculator has two keys: D, which doubles the number, and T, which erases the digit of the units. If a person writes 1999 and then press D, T, D, and T in sequence, which number will it be?

*Difficulty level:*

A calculator has two keys: D, which doubles the number, and T, which erases the digit of the units. If a person writes 1999 and then press D, T, D, and T in sequence, which number will it be?