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Calculate sample and population standard deviation and variance from any data set with squared-deviation steps.

Find the mean, median, and mode of any data set with frequency tables, sorted data, and step-by-step work.

Convert numbers to and from scientific notation, e-notation, and engineering notation. Enter decimals (299792458), e-notation (1.23e-5), or 1.23 × 10^5 format. Get normalized scientific, Unicode superscript, engineering (×10³), and decimal forms. Adjustable significant figures. Free, browser-based.

Count significant figures, round to N sig figs, and add, subtract, multiply, or divide with correct precision rules. Enter decimals, trailing zeros, or scientific notation. Free, instant, browser-based.

Combine and propagate measurement uncertainty with root-sum-of-squares (RSS). Add, subtract, multiply, or divide values with ± uncertainties, convert percent uncertainty, and compute expanded uncertainty U = k·u. Free, instant, browser-based.

Calculate percent error, absolute error, relative error, and percent difference between measured and accepted values. Step-by-step formulas for physics and chemistry lab reports. Free, instant, browser-based.

Calculate sample size for surveys, mean estimates, A/B tests, and two-group comparisons. Set confidence level, power, margin of error, and effect size. Step-by-step formulas. Free, browser-based.

Plot data as line, scatter, or bar charts from x,y pairs or separate columns. Enter lab results, calibration curves, or trial data — get an instant SVG chart with axis labels. Free, browser-based.

Graph mathematical functions y = f(x) instantly. Enter expressions like sin(x), x^2, exp(x), or multiple functions — get an SVG plot with axes, grid, and auto-scaling. Free, browser-based.

Free mental math drill practice tool — timed addition, subtraction, and multiplication with live score and streak. Press Enter for the next problem.

Free times tables trainer — pick a multiplication table from 2 to 12, practice random prompts, and track your mastery percentage.

Free unit conversion practice tool — convert between km and mi, °C and °F, and more. Check answers with tolerance and see a worked step.