Giáo Dục & Toán Học
Các máy tính toán học và thống kê với công thức từng bước và ví dụ minh họa dành cho học sinh, sinh viên và người đi làm.
Máy Tính Phần Trăm
Tính phần trăm theo ba cách: tìm phần trăm của một số, tìm một số là bao nhiêu phần trăm của số khác, hoặc tính phần trăm thay đổi giữa hai giá trị.
Percentage Increase Calculator
Calculate percentage increase between two values with the standard formula, a worked step-by-step example, and the absolute difference shown alongside.
Percentage Decrease Calculator
Calculate percentage decrease between two values with the standard formula, a worked example, and the absolute difference shown alongside the result.
Fraction Calculator
Add, subtract, multiply and divide fractions with automatically simplified results, the decimal equivalent, and step-by-step formulas for each operation.
Decimal to Fraction Calculator
Convert any terminating decimal to a simplified fraction with the place-value method, plus the equivalent percentage. Example: 0.625 = 5/8 = 62.5%.
Ratio Calculator
Simplify a ratio to lowest terms, express it in 1:n form, and scale it to a new first term. Example: 4:6 simplifies to 2:3 and scales to 10:15.
Average Calculator
Calculate the average (arithmetic mean) of a list of numbers, with the sum, count, minimum and maximum shown alongside. Includes a worked example.
Scientific Calculator
Free online scientific calculator: trig in radians or degrees, roots, logs, exponents, constants pi and e — evaluated with a safe whitelist expression parser.
Mean Calculator
Calculate the arithmetic, geometric and harmonic means of a data set, with formulas, a worked example, and guidance on when each mean is appropriate.
Median Calculator
Find the median, mode and range of a data set with worked examples. Handles even-sized lists and multiple modes, and explains median vs mean for skewed data.
Standard Deviation Calculator
Calculate sample and population standard deviation, variance and mean for any data set, with the n-1 vs n distinction explained and a worked example.
Probability Calculator
Calculate the probability of two independent events: both occurring, either occurring, neither occurring, and the complement — with formulas and examples.
Sample Size Calculator
Calculate the survey sample size you need using Cochran's formula with finite population correction, at 90%, 95% or 99% confidence and your margin of error.
Confidence Interval Calculator
Calculate a z-based confidence interval for a mean from the sample mean, standard deviation and size, with the margin of error and standard error shown.
Z-Score Calculator
Calculate a z-score from a value, mean and standard deviation, plus the normal-distribution percentile and the share of values above. Worked example inside.
Quadratic Equation Calculator
Solve ax^2 + bx + c = 0 with the quadratic formula. Shows real or complex roots and the discriminant, with a worked step-by-step example.
Log Calculator
Calculate logarithms in any base with the change-of-base formula, plus the natural log (ln), common log (log10) and binary log (log2) shown together.
Exponent Calculator
Raise any base to any power, including negative and fractional exponents, with the result in plain and scientific notation and the exponent rules explained.
Prime Number Calculator
Check whether a number is prime, get its full prime factorization, and find the next prime — with trial division explained and worked examples.
Matrix Calculator
Calculate the determinant, trace and (for 2x2) inverse of a 2x2 or 3x3 matrix from row-major entries, with cofactor expansion shown step by step.