Long Multiplication Calculator
Calculate long multiplication instantly in your browser.
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What this tool does
Calculate long multiplication instantly in your browser. Whole numbers only; the table shows one partial product per digit of the second number.
How to use the Long Multiplication Calculator
- Enter or select first number.
- Enter or select second number.
- Read the calculated result; change any measurement to compare alternatives.
Formula
Multiply the first number by each digit of the second (shifted by its place value) to get partial products, then add the partial products.
- a
- First number
- b
- Second number
Whole numbers only; the table shows one partial product per digit of the second number.
Worked example
For long multiplication calculator, the following measurements illustrate the exact method: First number: 123; Second number: 45.
Inputs
- First number123
- Second number45
Result
- Product5,535
- Partial products sum5,535
Results explained
- Product
- Product from the formula above. Whole numbers only; the table shows one partial product per digit of the second number.
- Partial products sum
- Partial products sum from the formula above. Whole numbers only; the table shows one partial product per digit of the second number.
Frequently asked questions
Multiply the first number by each digit of the second (shifted by its place value) to get partial products, then add the partial products.
Whole numbers only; the table shows one partial product per digit of the second number.
Where mathematically meaningful, yes. Fields specify permitted ranges and undefined operations display an error.
Exact integer calculations use safe integers; decimal calculations use browser floating point, so small rounding differences can occur.
All values remain in your browser and are never uploaded.