Convert integers from 0 to 255 between four bases. Choose a pair or mix the bases, check your answer and move on when you are ready.
Settings apply to the next new exercise. Retry keeps the current challenge.
Start an exercise, read the source and target bases and enter your answer. Choose Check to test your reasoning. A wrong answer keeps the question for another attempt; a new challenge only appears when you choose an action.
Counters apply to this session. Each distinct wrong answer counts once per challenge; checking the same answer again does not add errors. Using a hint or revealing the solution marks the exercise as assisted. Retry starts a fresh attempt at the same challenge.
The base determines the available digits and the weight of each position. Binary uses 0 and 1; octal uses 0 to 7; decimal uses 0 to 9; hexadecimal uses 0 to 9 and A to F. From right to left, the weights are base⁰, base¹, base² and so on.
Decimal 10 = binary 1010, because 10 = 1×2³ + 0×2² + 1×2¹ + 0×2⁰. In reverse, binary 1010 = decimal 10.
Hexadecimal FF = decimal 255, because 15×16 + 15 = 255. Decimal 64 = octal 100, because 1×8² = 64. These are separate teaching examples, not an automatic solution to the active challenge.
Do not confuse decimal 10 with binary 10. The digit 2 is not binary, and 8 is not octal. Do not use 0b/0x prefixes or separators inside a number. Hexadecimal letters may be uppercase or lowercase.
Exercises only use nonnegative integers from 0 to 255, without precision loss in this range. The whole answer is validated: a valid prefix followed by invalid characters is not accepted.