Deg (degrees) — 0 to 360, what you learned in school. A right angle is 90°. Use this for everyday angles.

Rad (radians) — 0 to about 6.28 (which is 2π). Used in calculus, physics, and engineering. A full circle = 2π radians.

If you're not sure, leave it on Deg.

sin, cos, tan — Given an angle, returns a ratio. Example: in Deg mode, sin(30) = 0.5.

sin⁻¹, cos⁻¹, tan⁻¹ — The reverse. Given a ratio, returns the angle. Example: sin⁻¹(0.5) = 30 in Deg mode. Use these when you know the ratio of two sides of a triangle and need the angle.

√x — Square root. √(25) = 5.

x² — Squares the number. 7² = 49.

xʸ — Raises x to the power y. Press 2 xʸ 10 = 1024.

1/x — Reciprocal. 1/4 = 0.25.

π (pi) ≈ 3.14159. The ratio of a circle's circumference to its diameter. Anywhere circles or waves appear.

e ≈ 2.71828. Euler's number. Shows up in compound interest, population growth, and natural logarithms.

log — Base-10 logarithm. log(1000) = 3 (because 10³ = 1000). Used in pH, decibels, the Richter scale.

ln — Natural log (base e). ln(e) = 1. Used in growth/decay, half-life, and calculus.

n! — Factorial. 5! = 5 × 4 × 3 × 2 × 1 = 120. Used in combinations and probability.

EXP — Scientific notation entry. 1.5 EXP 6 = 1.5 × 10⁶ = 1,500,000. Handy for very big or very small numbers.

Ans — The last calculated result. Reuse it in your next calculation without retyping.

± — Flips the sign of the current number (positive ↔ negative).

M+ — Add the current value to memory.

M− — Subtract the current value from memory.

MR — Recall (paste) the stored value back into the display.

MC — Clear memory (resets stored value to 0).

Memory is great for running totals — e.g. add several subtotals into M, then MR at the end.