Math
1,470 math calculators: percentages, fractions, equations, geometry, trigonometry, statistics and number theory. Each one shows the method in plain words, so you get the answer and understand how it was reached, free in your browser.
Wilcoxon signed-rank test calculator
Test paired measurements, such as before-and-after readings, without assuming normal differences: for 6 pairs whose positive ranks sum to 19 and negative ranks…
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Two-Proportion Z-Test Calculator
Compare two success rates from independent groups: 56 out of 100 against 42 out of 100 gives proportions of 0.56 and 0.42 and a pooled rate of 0.49, plus the z…
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Eta squared calculator
A between-group sum of squares of 24 out of a total of 80 gives an eta squared of 0.3: the grouping factor accounts for 30 % of the observed variance.
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Odds Ratio Calculator for a 2x2 Table
If 30 people in group 1 have the outcome and 70 do not, against 20 and 80 in group 2, the odds ratio is 2400 over 1400, so the odds are higher in group 1.
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Weighted moving average calculator
Smooth an ordered series with a sliding weight pattern: with weights 1, 2 and 1, each window covers 3 values, the middle one counts double and the sum is…
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Atkinson Index Calculator for Income Inequality
An Atkinson index of 0.20 means an equal split at 80 percent of today's mean income would give the same welfare.
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Double Exponential Smoothing Calculator
When a series opens with 10 and 12, Holt's method starts from a level of 10 and a trend of 2 per period, updates both with every new value and projects as many…
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Kullback-Leibler Divergence Calculator for Probability Distributions
Measure how far a probability distribution P strays from a reference Q, in nats: identical distributions give 0, and swapping P and Q usually changes the…
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Two-argument arctangent calculator in degrees
A vector with x of −1 and y of 1 points at 135°, up and to the left. Enter both coordinates, y first and then x, and get the angle in degrees between −180 and…
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Cotangent of an angle in radians calculator
Enter 0.7853981633974483 radians, a quarter of pi, and the cotangent comes back as 1, with sine and cosine of 0.707106781187 each.
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Right triangle from hypotenuse and angle calculator
Finish a right triangle from just two values: a hypotenuse of 10 with a 30° angle gives an opposite leg of 5 and another acute angle of 60°, plus the adjacent…
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Sine of an angle in radians calculator
Get the sine of an angle given in radians: π/2 returns exactly 1, a quarter turn to the top of the unit circle.
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Ladder angle against wall calculator
Know how steep your ladder stands before you climb: a 5 m ladder with its foot 3 m from the wall leans at about 53.13° to the ground.
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Shadow length from sun angle calculator
Know how far a shadow reaches before you plan shade or a photo: a pole 2 metres tall with the Sun 45° above the horizon casts a shadow 2 metres long.
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SSA number of triangles calculator
Know how many triangles your SSA data allow before you solve: sides of 10 and 16 with a 30° angle give an altitude of 8, so two different triangles fit.
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Cosine of a difference calculator
Find cos(A − B) from two angles: for A of 60° and B of 30° the result is 0.866025403784, the sum of two products of 0.433012701892 each.
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Cosine Half-Angle Calculator
If cos(θ) is 0.5 and the half-angle lies in quadrant II, cos(θ/2) is about −0.8660254037844386: the square root gives the size and the quadrant settles the…
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Solve A sin(Bx) + C equation calculator
Get every root in your range, not just one: 2 sin(x) equals 1 between 0° and 360° has two roots, 30° and its supplementary angle.
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Sum-to-product sine calculator
Turn a sum of two sines into a product: sin 50° + sin 10° becomes 2 sin 30° cos 20°, with the half-sum and half-difference shown and both forms evaluated to…
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Triangle area from two sides and included angle calculator
Sides of 3 and 4 with a 90° angle between them enclose an area of 6. Enter two side lengths in one unit and the included angle in degrees to get the triangle's…
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Radians to gradians conversion calculator
Move an angle from radians to the 400-part circle in one step: π radians become exactly 200 gradians, a straight angle.
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Midpoint of polar coordinates calculator
Find the true halfway point between two radius-and-angle positions: points at the same distance at 350° and 10° meet in the middle at 0°, not at 180° as a plain…
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Exponential growth model solution calculator
Start with 100 and a continuous rate constant of 0.05 per unit of time, and after 10 units the solution of dA/dt = kA gives 164.87212707, with the exponent 0.5…
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Runge-Kutta 2 ODE Solver Calculator
Starting at y(0) = 1, four midpoint steps of 0.1 carry y' = x + y to 0.4 and give 1.58180410125. Choose the midpoint, Heun or Ralston rule, and every slope and…
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Involute function
Enter a pressure angle in radians and get its involute, tan(a) minus a: 20 degrees, which is 0.3490658503988659 radians, gives 0.014904383867.
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Irregular polygon area calculator
List the corners of a straight-sided shape in boundary order and get its area: the L-shaped outline (0, 0), (6, 0), (6, 2), (3, 5), (0, 2) encloses 21 square…
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Irregular trapezoid area calculator
Measure the two parallel sides and the gap between them to get the area of any trapezoid, crooked legs included: bases of 10 and 6 metres, 4 metres apart, give…
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Is modulo associative?
Find out whether the grouping changes a chained remainder: for 17, 5 and 3, (17 % 5) % 3 gives 2 but 17 % (5 % 3) gives 1, so the answer is no.
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Isosceles right triangle calculator
Give one side of a right triangle with two equal legs and get the side you are missing: a leg of 5 gives a hypotenuse of 7.0710678119, because the sides always…
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Isosceles triangle angles
Enter the vertex angle of an isosceles triangle and get its two equal base angles: a 40° vertex leaves 140° to share, so each base angle is 70°.
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Isosceles triangle area calculator
Give the base and the length of the two equal sides and get the area of an isosceles triangle: a base of 10 with sides of 13 has a height of 12 and an area of…
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Isosceles triangle area calculator
Enter the base and the equal sides of an isosceles triangle to get its height and area together: a base of 6 with sides of 5 gives a height of 4 and an area of…
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Isosceles triangle height calculator
Enter the base and one of the equal sides of an isosceles triangle and get its height: a base of 10 with sides of 13 rises 12 units to the apex.
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Isosceles triangle side calculator
Enter the base and the height of an isosceles triangle and get the length of its two equal sides: a base of 6 and a height of 4 give sides of 5, the 3-4-5 right…
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Lagrange error bound calculator
Give a bound M on the derivative, the interpolation nodes and the point you care about, and get the largest error the polynomial can have there: nodes 0, 1 and…
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Lateral area of a cone
Give the base radius and the slant height of a cone and get the area of its curved side only, without the base: a radius of 3 and a slant height of 5 give…
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Lateral area of a trapezoidal prism calculator
Add the four sides of a trapezoidal cross-section and multiply by the length to get the area of the prism's four side faces: sides of 10, 6, 5 and 5 with a…
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Lateral surface area of a cylinder
Enter the radius and height of a cylinder and get the area of its curved side alone, without the two ends: a radius of 4 and a height of 10 give 251.3274122872.
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Latus rectum calculator
Enter the coefficients of a parabola, or of an ellipse centred at the origin, and get the length of its latus rectum: for the parabola 0.25·x² it is 4, the…
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Law of cosines calculator
Give two sides and the angle between them to get the third side, or all three sides to get an angle: sides of 5 and 7 meeting at 60° leave a third side of…
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Length and width of a rectangle from perimeter and side ratio
Enter a rectangle's perimeter and the ratio of its sides and get both dimensions: a perimeter of 36 with a 2 to 1 ratio gives a length of 12 and a width of 6.
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Big integer addition calculator
9223372036854775807 plus 1 is exactly 9223372036854775808, a sum that overflows a signed 64-bit integer but is kept here digit by digit.
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Round to nearest multiple
23 rounded to the nearest multiple of 5 is 25. Pick any step, from 5 or 10 down to 0.25, and the calculator snaps your number onto it, shows the multiples on…
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Long addition calculator
Add two whole numbers the way it is done on paper, column by column with every carry shown: 456 plus 789 gives 1245, with three carries.
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Long subtraction calculator
Subtract whole numbers column by column, the way it is taught at school: 905 minus 187 gives 718 with two borrows.
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Lowest common denominator calculator
Find the smallest denominator a list of fractions can share: for 1/2, 1/3 and 1/4 it is 12, which gives 6/12, 4/12 and 3/12.
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Fraction to Lowest Terms Calculator
Reduce any fraction to its simplest form in one step: 42/56 becomes 3/4, because both numbers divide by 14.
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Luhn algorithm validator
Find out at once whether a digit string passes the Luhn mod-10 check: 79927398713 does. It catches any single mistyped digit and most swaps of neighbouring…
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Magic square generator
Build an odd-order magic square in which every row, column and main diagonal has the same sum: the 3×3 square adds up to 15 and the 5×5 to 65.
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Power calculator
Raise a base to an exponent and get one finite number: 2 to the 10th is 1024 and 9 to the power one-half is 3.
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Matrix calculator
Add, subtract or multiply two matrices of up to fifty rows and fifty columns: adding the 2×2 matrices 1, 2, 3, 4 and 5, 6, 7, 8 gives 6, 8, 10, 12.
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Matrix norm calculator
Sum up a matrix in one number: for the rows 1, −2, 3 and 4, 0, −1, the infinity norm is 6 and the one norm is 5.
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Mayan numeral converter
Turn a whole number into Mayan dots and bars: 429 becomes one dot in the four-hundreds row, one dot in the twenties row and a bar with four dots for the units.
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Midsegment of a triangle calculator
Halve the side parallel to a triangle's midsegment and you have the midsegment itself: a parallel side of 18 units gives a midsegment of 9.
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Minutes to decimal degrees calculator
Turn the minutes part of an angle into decimal degrees by dividing by 60: 30 minutes is 0.5 degree and 15 minutes is 0.25.
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Mixed Number to Improper Fraction Calculator
Turn a mixed number into an improper fraction by multiplying the whole part by the denominator and adding the numerator, so 3 and 2/5 becomes 17/5.
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Integer palindrome checker
Check whether a whole number reads the same both ways: 121 and 3443 do, 10 and 123 do not. You also see the digits and their reverse, so the verdict can be…
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Missing side of a right triangle
Find the third side of a right triangle from the two you know: legs of 3 and 4 give a hypotenuse of 5, and a hypotenuse of 13 with a leg of 5 gives 12.
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Mixed number converter
Rewrite an improper fraction as a whole number plus a leftover: 11/4 becomes 2 3/4, and the leftover is reduced, so 10/4 gives 2 1/2.
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Modulo order of operations calculator
Evaluate an expression with +, −, ×, ÷ and the % remainder in the standard order: 2 + 3 * 4 % 5 is 4, because 3 * 4 % 5 is worked out first, left to right.
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