How to Use a Scientific Calculator Effectively

A scientific calculator is useful when a problem contains more than basic arithmetic: angles, logarithms, powers, roots, scientific notation or repeated calculations.

1. Start with the correct angle mode

Trigonometric functions depend on the angle unit. Use DEG when the problem gives degrees and RAD when it uses radians. A common source of wrong answers is calculating a degree problem while the calculator is in radians.

2. Respect order of operations

Multiplication and division are evaluated before addition and subtraction. Parentheses make your intention explicit. For example, 12 / (3 + 1) is 3, while 12 / 3 + 1 is 5.

3. Know the common scientific functions

• sin, cos, tan: trigonometric ratios.
• log: base-10 logarithm.
• ln: natural logarithm, base e.
• sqrt: square root.
• ^: exponentiation.
• ! factorial for non-negative integers.

4. Check the result

Do a rough mental estimate before trusting a long calculation. If the result is wildly outside the expected range, check signs, parentheses, angle mode and units.