The converter walks the number in groups of three digits, naming each group (units, thousands, millions, billions, trillions) using the modern short scale used in US and UK English. Numbers below 100 are emitted directly from a lookup table for the irregular forms (eleven, twelve, fifteen, twenty, thirty…), and the result is concatenated with the correct scale word. Common applications include filling in cheque amounts, drafting legal contracts, generating speech-friendly numerals, or producing accessible labels for screen readers.
Internally the converter floors the input to an integer and recursively breaks it into groups of three digits, calling a small lookup-based function for each group. Negatives are handled by stripping the sign and prefixing the word "negative". Inputs above 10^15 are rejected because JavaScript's IEEE-754 Number type begins losing precision on integers larger than 2^53 — silently producing wrong words would be worse than rejecting the input. Decimal portions are dropped (use a separate cents/fractional formatter if you need cheque-style "and 50/100").
The short scale used in modern US and UK English: 1,000,000,000 is "one billion" and 1,000,000,000,000 is "one trillion". The long scale (older European usage where a billion meant 10^12) is not supported.
Up to 999,999,999,999,999 — just under one quadrillion. Beyond that the converter shows a "too large" message because JavaScript's Number type starts losing integer precision past 2^53 (roughly 9 quadrillion).
A negative integer is converted as if positive and prefixed with the word "negative". So -42 becomes "negative forty-two" and -1000 becomes "negative one thousand".
The input is floored to an integer before conversion — decimal portions are dropped. For cheque-style amounts like "forty-two and 50/100" you would need to format the fractional part separately.
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