Math & Everyday

Clear, reliable mathematical tools for solving proportions, slope of lines, percentage changes, and retail discounts.

The calculators in this category are listed below. Each link opens the full calculator on CalcFree.

Calculators in this category

Solve for any missing value in a ratio (A : B = C : D) with step-by-step cross-multiplication, fraction reduction, and percentages.

How it is calculated: Cross Multiplication: If A / B = C / D, then A × D = B × C. Unknown X = (B × C) ÷ D

Find the slope (m), angle, distance, and line equation (y = mx + b) passing through any two coordinate points (x₁, y₁) and (x₂, y₂).

How it is calculated: Slope m = (y₂ − y₁) ÷ (x₂ − x₁); Angle θ = arctan(m); Distance d = √[(x₂ − x₁)² + (y₂ − y₁)²]

Calculate the exact percentage rise or drop between two numbers, along with the absolute difference and multiplier factor.

How it is calculated: Percentage Change (%) = [(Final Value − Initial Value) ÷ |Initial Value|] × 100

Find your final price after applying store discounts, stacked coupons, and local sales tax so you know what you pay at the till.

How it is calculated: Discounted Price = Original Price × (1 − Discount% ÷ 100); Total Savings = Original Price − Final Price