Inspired by the last year's "2018 four 4s challenge", I thought it's time to welcome 2019 by a similar challenge. This time you have to use the digits 2, 0, 1, 9 in this particular order to create the numbers 1 - 30.
The rules haven't changed:
- Use all four digits exactly once in the order 2-0-1-9.
- Allowed operations: $+, -, \cdot, \div, !$ (factorial), $!!$ (double factorial), square root, exponentiation.
- Parentheses and grouping (e.g. "19") are also allowed.
- Squaring uses the digit 2, so expressions using multiple 2's, e. g. $2^2$ or $1^2+2^9$, are not allowed.
- The modulus operator $(\%, \mod)$ is not allowed.
- Rounding (e.g. 201/9=22) is not allowed.
I'm curious to see your creative solutions!
May each day of 2019 bring happiness, good cheer, and sweet surprises to you and all your dear ones!
Happy New Year and greetings from Germany! André