Round to Nearest Tenth Calculator

Enter Number to Round:

Resulting Value:

function calculateRoundTenth() { var input = document.getElementById("numberToRound").value; var resultArea = document.getElementById("roundResultArea"); var output = document.getElementById("roundingOutput"); if (input === "" || isNaN(input)) { alert("Please enter a valid numeric value."); resultArea.style.display = "none"; return; } var num = parseFloat(input); // Logic: Multiply by 10, round to whole number, then divide by 10 var rounded = Math.round(num * 10) / 10; // Format to show at least one decimal place even if it is zero output.innerHTML = rounded.toFixed(1); resultArea.style.display = "block"; }

Understanding Rounding to the Nearest Tenth

Rounding to the nearest tenth means simplifying a number to one decimal place. This is a common mathematical practice used to make numbers easier to work with while maintaining a high level of accuracy for scientific, financial, and statistical data.

The Mathematical Rule

To round a number to the nearest tenth, you must look at the digit in the hundredths place (the second digit to the right of the decimal point):

If the hundredths digit is 5 or greater: Increase the tenths digit by 1 (Round Up).
If the hundredths digit is less than 5 (0, 1, 2, 3, or 4): Keep the tenths digit the same (Round Down).

Real-World Examples

Example 1: 15.44
The hundredths digit is 4. Since 4 is less than 5, we keep the .4 as it is.
Result: 15.4

Example 2: 7.86
The hundredths digit is 6. Since 6 is 5 or greater, we round the .8 up to .9.
Result: 7.9

Example 3: 102.05
The hundredths digit is 5. Following the "5 or more" rule, the .0 becomes .1.
Result: 102.1

Example 4: 9.98
The hundredths digit is 8. Rounding up the .9 results in 10.0.
Result: 10.0

Why Round to the Nearest Tenth?

Rounding is essential in many fields. In meteorology, temperatures are often reported to the nearest tenth (e.g., 98.6°F). In track and field, race times are frequently measured to the nearest tenth or hundredth of a second. Using a tenth calculator ensures that your data remains standardized and prevents "precision inflation" where too many decimal points provide no extra value to the reader.