Mathe & Geometrie

58 Rechner

Days Between Two Dates Calculator

Calculate the number of days between two specified dates quickly and accurately.

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Rule of 72 Calculator

Estimate doubling time from a growth rate, or implied rate to double in N years. Educational mental math only.

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Final Exam Grade Calculator

Weighted grades: what you need on the final to reach a target course grade.

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Simple GPA Calculator

Enter grade points and credits per line; computes weighted GPA on a 4.0-style scale.

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Freelance Hourly Rate Calculator

Target annual income, billable weeks/hours, and buffer % to a suggested hourly rate.

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Proportion Calculator

Solve a:b = c:x for x (cross-multiply: x = b×c÷a).

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Random Number Generator

Integer range, how many numbers, optional unique draws (≤ range size).

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Roman Numeral Calculator

Convert Arabic numbers to Roman numerals and parse common Roman strings back.

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Split Bill Calculator

Total bill, headcount, and optional tip percent—per person share.

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Circle Area Calculator

Radius → area πr² and circumference 2πr in consistent units.

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Right Triangle Calculator

Two legs of a right triangle—hypotenuse and area.

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Square Root

Principal square root for non-negative real x.

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Dew Point (Magnus)

Air temperature °C and RH%—approximate dew point for planning.

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Password Entropy

Character pool size and length—approximate bits of entropy.

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GCD and LCM

Greatest common divisor and least common multiple of two integers.

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CM to Pixels

Physical length in cm and DPI—pixel count along that edge.

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Factorial (n ≤ 20)

Small factorials for combinatorics homework checks.

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Combinations n choose r

Binomial coefficient C(n,r) with a stable multiplicative formula.

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Golden Ratio Layout

Given long or short side, find the other for φ ≈ 1.618 proportions.

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Rectangular Prism Volume

Length × width × height in consistent units.

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Cylinder Volume

π r² h for a right circular cylinder.

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Sphere Volume

(4/3) π r³ from radius.

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Slope from Two Points

Two (x,y) pairs—slope m (vertical line excluded).

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Midpoint of Two Points

Average of coordinates—center between two points.

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Binary to Decimal

Binary string of 0s and 1s to a decimal integer.

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Decimal to Binary

Non-negative integers up to about 2²⁰ to binary text.

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Hex to Decimal

Hex string (optional 0x) to a decimal integer.

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Decimal to Hex

Non-negative integers up to 2³²−1 to uppercase hex.

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Octal to Decimal

Base-8 digit string to a decimal integer.

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Decimal to Octal

Non-negative integers up to 2³¹−1 to octal text.

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log₁₀(x)

Common logarithm for positive x.

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Powers of Ten (10^x)

Exponent x—ten to the x power (limited range).

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TV Viewing Distance

Diagonal inches (16∶9)—rough min–max distance in feet.

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Add R-Values

Up to three insulation layers—approximate total R.

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Permutation P(n,r)

Ordered arrangements—n choose r with ordering.

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Fraction Addition

Add two fractions and reduce to lowest terms.

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Z-Score

Value, mean, and standard deviation—standardize a score.

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Random String

Length and charset—tokens and test IDs (not crypto secrets).

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Cylinder Surface

Radius and height—lateral and total surface area.

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String Length

UTF-16 units vs Unicode code points.

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Word Count

Whitespace word count.

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Heron Area

Three sides → triangle area.

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Inverse Square

Intensity ratio vs distance change.

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Hex → RGB

Parse #RGB / #RRGGBB.

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Hypotenuse

√(a²+b²) for a right triangle.

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Ellipse Area

π times semi-major times semi-minor.

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Cylinder Volume

πr²h for a right circular cylinder.

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Sphere Surface

4πr² from radius.

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Arc Length

Fraction of circumference from central angle.

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Sector Area

Pie-slice area from r and θ°.

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Third Angle

180° minus two known angles.

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Coterminal Angle

Same terminal side in [0,360).

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Polar Distance

Euclidean distance in the plane.

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log₂(x)

Binary log for positive x.

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ln(x)

Natural log for positive x.

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Harmonic Mean

Two-number harmonic average.

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Polygon Interior

Each interior angle for regular n-gon.

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Dreisatzrechner

Rule of three: direct, inverse, and percent proportions — multilingual (German default, English and more).

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