gNumerator
Science, Math, Software, Calculators - gNumerator. A interactive computer math system that uses standard JavaScript as the scripting language, and a collection of re-usable math oriented components such as a complete MathML DOM implementation, and a MathML viewing / editing control.
https://numerator.sourceforge.net/
GIGACalculator.com: Online Calculators and Converters
Science, Math, Software, Calculators - Online Calculators & Converters. A big collection of free online calculators with all kinds of applications: mathematics, geometry, finance, construction, transportation, health & fitness, physics, chemistry.
https://www.gigacalculator.com/
Percentage Calculator
Science, Math, Software, Calculators - Percentage Calculator. Percentage calculator is your free online tool to calculate percentages easily.
https://www.percentagecal.com/