Convert instantly between the four most-used number systems.
Binary (base 2) uses 0 and 1. Hexadecimal uses 0-9 and A-F.
Computers process everything in binary code internally.
Use this calculator whenever mental arithmetic introduces uncertainty — particularly when the result will inform a decision rather than just satisfy curiosity. Even confident mathematicians use calculation tools when precision matters.
A common mistake is applying the formula in the wrong direction — particularly with percentage and ratio problems, where the part and the whole can be mistakenly swapped. Check which value is the reference (the 'whole') before entering inputs.
A shopper sees two versions of the same product at different prices: one at £14.50 for 400g and another at £11.99 for 300g. Running both price-per-gram calculations reveals the larger pack is 7% cheaper per unit — the kind of comparison that is impossible to do reliably in your head at the shelf.
255 in decimal = 11111111 in binary.
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