Exact whole-number written multiplication
Long Multiplication Calculator
Multiply two signed whole numbers with digit-by-digit partial products, place-value shifts, carries, and a readable vertical layout.
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Enter known values
Signed whole numbers only, up to 200 digits each. Scientific notation and decimals are not accepted.
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Text steps
Method
Each multiplier digit is multiplied across the multiplicand from right to left with an explicit carry. Each exact digit string is shifted by its decimal place and the partial rows are added with string arithmetic. The final sign is applied after magnitude multiplication.
Limitations
V1 accepts signed integers only. It never converts operands to JavaScript Number, so supported large integers retain every digit. Inputs are capped at 200 digits each to bound rendering and work. It does not accept decimals, exponents, expressions, or handwriting.
Privacy
No account, server calculation, remote API, fetch, XHR, beacon, cookie, local storage, session storage, IndexedDB, or user-value telemetry is used.