About

Standard calculators and programming languages often struggle with simple decimal math due to the way computers store numbers (IEEE 754 floating-point standard). A classic example is 0.1 + 0.2, which computers often calculate as 0.30000000000000004. While tiny, these errors accumulate rapidly in financial reports or scientific datasets.

This tool bypasses standard floating-point limitations by treating numbers as strings and performing arbitrary-precision arithmetic (simulating manual calculation). It is designed for accountants, scientists, and data analysts who need to sum massive lists of decimal numbers with 100% accuracy, maintaining precision down to the last decimal place.

Formulas

The core issue with binary floating-point is the inability to represent certain fractions precisely:

0.1₁₀ ≈ 0.0001100110011...₂

This calculator scales values to integers before summing to ensure:

Sum = (A × 10^k + B × 10^k) ÷ 10^k

Reference Data

Operation	Standard Output (JS/Python)	High-Precision Output	Error
0.1 + 0.2	0.30000000000000004	0.3	Yes
1.005 * 1000	1004.9999999999999	1005	Yes
Sum of 10,000 prices	$14,500.000002	$14,500.00	Yes

Frequently Asked Questions

Yes. Simply copy a column of numbers from Excel or Google Sheets and paste it into the text area. The tool automatically detects line breaks and ignores currency symbols like "$" or ",".

This tool adapts to the input. If you add a number with 20 decimal places, the result will preserve those 20 places (and potentially more if carrying occurs). It does not artificially truncate results unless you ask it to.

Computers work in binary (Base-2). Just as 1/3 cannot be written neatly in decimal (0.333...), 1/10 (0.1) cannot be written neatly in binary. It results in a repeating fraction that gets chopped off, creating a tiny error.