Eight notes. One daily discovery.

Find a six-digit octal code in six guesses. Octal is base 8, so each box holds a digit from 0 to 7. Leading zeroes and repeated digits are allowed. You can solve the puzzle without converting numbers or reading music.

Make your first guess

Tap the eight number keys or type 0–7 on your keyboard, then choose Make a guess. Fill all six boxes before submitting. Tap a box in your active row to replace its digit; the delete button removes the last digit.

Read the colours

• Green: the right digit in the right position. Keep it there.
• Yellow: this copy of the digit belongs in a different position.
• Grey: the digit is absent, or you have guessed more copies than the answer contains.

Repeated digits are counted carefully. If the answer contains only one 3, guessing several 3s will not earn several green or yellow tiles for it.

Follow the arrows

With Arrow help on, each non-green tile shows an arrow beneath its digit: ↑ try a higher digit, or ↓ try a lower digit. It compares the secret digit in that exact position, not the whole six-digit number. The arrow is useful even on a grey tile.

Use the Arrow help switch at the top of the puzzle. On makes it easier; off leaves only colour clues for a harder challenge. You can switch at any time without losing your guesses.

Find the tune

The digits map to 0 = C, 1 = D, 2 = E, 3 = F, 4 = G, 5 = A, 6 = B, 7 = the higher C. Sound starts off. Turn it on to hear the digits you enter, or use Hear the octave to listen to all eight notes.

The sounds during play belong to your own guess. They do not reveal an unguessed answer, and listening is never required to solve the game. After finishing, you can hear the answer as a six-note phrase, discover its decimal value and sourced fact, and choose See the bits to unfold each digit into three binary bits.

Today, Practice and sharing

Today's puzzle changes at midnight in London. Completed and unfinished guesses are saved in this browser, separately from the other Noughts games. Practice opens another puzzle with separate progress. Shared results show the colour grid without your guesses, answer or melody.

Each daily puzzle has its own music discovery. Use the calendar for earlier games; Practice uses only released discoveries. Six digits. Eight notes. No audition required.