Free Online Calculator Suite

A basic calculator handles the four fundamental arithmetic operations — addition, subtraction, multiplication, and division — plus a percentage key and memory functions. While smartphones have made calculators ubiquitous, understanding the underlying operations and common mistakes helps you use any calculator accurately.

Order of operations (PEMDAS/BODMAS): mathematical expressions follow a strict hierarchy. Parentheses first, then Exponents, then Multiplication and Division (left to right), then Addition and Subtraction (left to right). Many people incorrectly calculate expressions like "2 + 3 × 4" as 20 (adding first) when the correct answer is 14 (multiplying first). Our calculator follows proper order of operations automatically.

Percentage key usage: on most calculators, the % key works differently depending on context. In addition/subtraction: entering "100 + 10%" calculates 10% of 100 and adds it = 110. In multiplication: "100 × 10%" calculates 10% of 100 = 10. This context-dependent behavior confuses many users.

Memory functions (M+, M-, MR, MC): M+ adds the current display value to memory. M- subtracts from memory. MR recalls the stored memory value. MC clears the memory. Useful for multi-step calculations where you need to reuse a partial result — for example, calculating the subtotal before tax, storing it, calculating the tax separately, then recalling the subtotal to add the tax.

Common calculation mistakes to avoid: not clearing the calculator between separate problems (leading to residual numbers in memory or display), misplacing decimal points (a single digit error can change an answer by a factor of 10), and not checking reasonable range of expected answers (if you're dividing $500 by 25 guests and the calculator shows $2 instead of $20, something went wrong).