MODULUS / REFERENCE
Formulas: Basic mathematics
Complete Android Modulus reference: formulas for Basic mathematics.
Percentages and ratios
• p% of A: B = A · p / 100
• Percentage ratio: p = B / A · 100%
• Proportion: a / b = c / d
Averages and powers
• Arithmetic mean: x̄ = (x1 + … + xn) / n
• Square of a sum: (a + b)² = a² + 2ab + b²
• Difference of squares: a² − b² = (a − b)(a + b)
Geometry
• Circumference: L = 2πr
• Circle area: S = πr²
• Rectangle area: S = ab
• p% of A: B = A · p / 100
• Percentage ratio: p = B / A · 100%
• Proportion: a / b = c / d
Averages and powers
• Arithmetic mean: x̄ = (x1 + … + xn) / n
• Square of a sum: (a + b)² = a² + 2ab + b²
• Difference of squares: a² − b² = (a − b)(a + b)
Geometry
• Circumference: L = 2πr
• Circle area: S = πr²
• Rectangle area: S = ab
Values are provided for reference. Check the required unit system and conditions before engineering or laboratory use.