Number Converters.

Turns any terminating decimal into an exact fraction in lowest terms. The input is read as text, so there is no floating-point rounding anywhere: 0.75 becomes 75/100 and is reduced by the greatest common divisor to 3/4. Improper fractions also come out as mixed numbers.

Use it for measurementsrecipeshomeworkworkshop math

Divides a fraction by long division and tells you what kind of decimal it produces. If the digits end, it's terminating; if a remainder repeats, the tool finds the repeating cycle and writes it in parentheses — the honest way to show 1/3.

Use it for ratiosodds & probabilitydivision practiceprecision checks

Converts in both directions across the full classical range, 1 to 3,999, using standard subtractive notation (IV, IX, XL, CM). Type roman numerals back and it parses them, checks whether the form is canonical, and shows the value broken into its symbols.

Use it for dates & chapterstattoos & engravingsmovie creditshistory class

Writes any integer up to the quadrillions in English words — with the short scale (one billion = 10⁹) — and handles negatives and decimal parts ("point four five"). It also produces the ordinal form: 26 becomes "twenty-sixth".

Use it for checks & invoiceslegal documentsinvitationsspeeches

The reverse journey: paste English number words and get digits back. It understands hyphens ("twenty-one"), commas, the connective "and", and "point" for decimals, then double-checks itself by spelling the result back out in words.

Use it for written amountscontract reviewtranscriptiondata cleanup

Base 2 in both directions. Alongside the conversion it shows hexadecimal, octal, the bit length, byte padding, and the popcount — how many 1-bits the number carries, which matters for bit flags and hashing.

Use it for programmingbit flagsnetworkinglogic design

One integer, six bases at once: binary (2), ternary (3), quinary (5), octal (8), duodecimal (12) and hexadecimal (16). The fastest way to build intuition for how positional notation works — the same quantity, six disguises.

Use it for computer sciencebase intuitionexam preppuzzles

Base 16 both ways, with the extras developers actually want: binary and octal forms, byte size, the ASCII character for single bytes, and — for values up to 0xFFFFFF — the matching CSS color code.

Use it for colors & CSSmemory dumpsserial protocolsdebugging