A decimal is another way to write a fraction whose denominator is a power of ten. Each position after the decimal point represents tenths, hundredths, thousandths, and smaller base-ten parts.
Decimals are useful for measurements, money, rates, and any calculation that needs parts of a whole written in base ten.
The calculator keeps the exact written scale through addition, subtraction, and multiplication. In division, it keeps the reduced fraction as the exact answer when a decimal would repeat.
Key idea
See the relationship
4.275=4 + 2/10 + 7/100 + 5/1000
Quick guide
How to use this calculator
Choose addition, subtraction, multiplication, or division.
Enter two signed decimal values.
Read the exact result and, for division, its decimal representation or labelled preview.
Calculation method
One exact decimal engine for four operations
Addition and subtraction align decimal scales, while multiplication combines them. Division converts both accepted decimals into an exact reduced fraction.
A fraction remains the exact division answer. Its decimal is labelled as exact only when complete; otherwise it is clearly presented as a truncated preview.
Worked example
Divide 1 by 8
The exact fraction is 1/8, whose decimal representation terminates.
1 ÷ 8 = 1/8 = 0.125
Supported inputs
Precision and limits
Exact decimal input
Each value may contain up to 200 digits, including up to 100 decimal places.
No hidden rounding
Accepted values use integer-backed decimal arithmetic rather than binary floating-point math.
Clear syntax
Enter plain decimal notation without grouping separators, fractions, or scientific notation.
Private by default
Your entries are calculated in this browser and are not submitted with the calculation.
