数学计算器

To find a percentage, divide the part by the whole and multiply by 100. For example, 50 out of 200 is (50 ÷ 200) × 100 = 25%. Use the Percentage Calculator for instant results.

Standard deviation measures how spread out numbers are. Find the mean, subtract it from each value, square the results, average them, then take the square root. Use the Standard Deviation Calculator for quick, accurate results.

Use the quadratic formula x = (-b ± √(b² - 4ac)) / 2a. Enter your coefficients a, b, and c into the Quadratic Formula Calculator and it will solve the equation with both real and complex roots.

Permutations count arrangements where order matters, while combinations count selections where order does not matter. Use the Permutation and Combination Calculator to compute both.