Scientific Calculator

It switches the keypad to each button's alternate (inverse) function, so one key can serve two purposes. With 2nd active, sin becomes arcsin (sin^-1), cos becomes arccos, and tan becomes arctan; ln becomes e^x, log becomes 10^x, sqrt becomes cube root, and x^2 becomes x^3. A purple '2nd' indicator appears while it is engaged. You can press 2nd again to cancel it, and it auto-resets after you use one alternate function so the next keystroke behaves normally. The inverse trig functions are essential when you know a ratio and need the angle that produced it — for example, arcsin(0.5) returns 30 degrees in DEG mode.

Use degrees for everyday geometry, surveying, and angles you read as whole numbers like 45, 90, or 180; use radians for calculus, physics, and any angle expressed as a multiple of pi. Both measure the same thing — a full circle is 360 degrees or 2*pi radians — but the calculator interprets your input according to whichever mode is selected. This is the single most common cause of 'wrong' trig answers: sin(90) returns 1 in DEG mode but about 0.894 in RAD mode, because in radians it is treating 90 as 90 radians, not 90 degrees. Always glance at the DEG/RAD indicator before a trig calculation, and switch modes if the result looks off.

They are logarithms with different bases: ln is the natural logarithm, base e (about 2.718), while log is the common logarithm, base 10. The base is simply the number that gets raised to a power — log(1000) is 3 because 10^3 = 1000, and ln(e) is 1 because e^1 = e. Each suits different problems: ln appears throughout calculus and in natural growth and decay, while base-10 log underlies the pH scale, decibels, and the Richter scale. On this calculator the log key means base 10. Note that some textbooks and software write 'log' to mean the natural log, so check the context whenever a source does not state the base explicitly.

Apply the formula A = P(1 + r/n)^(nt), where P is the starting amount, r is the annual rate as a decimal, n is the number of compounding periods per year, and t is the number of years. The keys to get right are parentheses and the power (x^y) button. Take $1000 at 5% compounded monthly for 10 years: enter 1000 x (1 + 0.05/12)^(12 x 10). The bracket evaluates to about 1.004167, raised to the 120th power gives roughly 1.6470, so A is about $1647.01. The order of operations handles the division and addition inside the parentheses first, then the exponent, then the final multiplication, so you can type it in one continuous expression.

That top line is a running record of the full expression you are entering, shown so you can read it back before committing. Because a scientific calculator evaluates the entire expression at once using the order of operations, seeing it written out lets you confirm the structure is what you intended — catching mismatched parentheses, a missing operator, or a function applied to the wrong term before they affect the answer. As you keep typing, the line grows to include every number, operator, and function. Once you press equals, the top line shows the completed 'expression =' for the record while the main display switches to the result, so you always have both the input and the output in view.