Build this number in binary
Click each bit to switch between 0 and 1.
How it works and a quick reminder
Decimal to binary
The computer chooses a decimal number. Click the bits to represent it. Use the optional place values if you need a hint. Add the values of the places containing a 1.
13 = 8 + 4 + 1 = 1101₂
Binary to decimal
The computer shows a binary number. Add the place values that contain a 1, then type the total. The displayed bits are the question, so they do not change in this mode.
1010₂ = 8 + 2 = 10
These are unsigned whole numbers: there are no negative values. Keep the leading zeros to show all 4, 6 or 8 bits. A 0 bit contributes nothing. An all-zero row represents zero.
Questions appear in a shuffled order. Every value at your chosen difficulty can appear before the set reshuffles. Changing direction or difficulty starts a fresh game. A wrong answer resets the first-try streak, but you can keep trying. Revealing an answer does not count as solving it.
Keyboard: Tab moves between controls. Space or Enter toggles a focused bit button. In decimal mode, Enter checks the typed answer.