Casio fx-CG50 field manual for IB Math
Common mistakes to avoid
The wrong minus key, the wrong angle mode, the wrong standard deviation, and each device's own classic traps, and what each wrong answer looks like.
The wrong minus key. The Casio has two: subtracts, and makes a number negative. Mix them up — 5 6 — and you get Syntax ERROR instead of an answer. The rule: only ever sits directly in front of a number (start of a line, after an operator, inside a bracket); everywhere else, subtraction is .
Templates hold the cursor. opens an exponent box, and the fraction key does the same: each box keeps the cursor until you step out. Type 2^5 then +3 straight away and the +3 lands inside the exponent: 25+3=256, not 25+3=35. Press to leave the box before continuing the line.
Scientific notation you didn't ask for. Two places small numbers turn scientific. On a reset or borrowed calculator still on the factory Norm1 display, everything below 0.01 does — 5×10−3 instead of 0.005 — which is why the settings page has you switch to Norm2. And the statistics result screens do it in every display mode: p-values arrive as 1.3499×10−3 no matter what. Either way, read the exponent rather than copying the mantissa alone — that transcription slip costs real marks exactly where p-values live.
The wrong angle mode. A new fx-CG50 is set to radians, so sin(30) means 30 radians: a degrees problem comes back as −0.988, impossible for an acute angle — and the status chip said Rad all along. Set Angle: Deg in SET UP ( ); it holds across every app. Maths AI SL uses degrees only, so this is a set-once fix.
Statistics on the wrong lists. The CALC menu computes from whatever its SET screen () last pointed at — and that memory persists between problems. If 1Var Freq still points at List 2 from last week's frequency table, today's raw data comes out silently wrong; if it is 1 when your frequencies sit in List 2, equally wrong the other way. Open SET and read 1Var XList and 1Var Freq before every 1-VAR press. And in the output, check which standard deviation you take: σx divides by n, sx by n−1.
Last session's leftovers. Apps reopen exactly where you left them. In Graph, old functions are still there and still selected, so they draw alongside today's — deselect or delete them with (SEL) and (DEL) first. The View Window also survives: if a graph looks blank or a root is missing, the answer is usually off screen — open (V-Window) and press (INITIAL) or (STD) to reset to a known view before hunting further.
A decimal where an exact answer was asked for. Run-Matrix answers exactly — fractions, surds, multiples of π — and flips between the exact form and its decimal. But everything read off a graph (G-Solve roots, intersections, maxima) is decimal only. When a question says "exact", do the algebra and finish in Run-Matrix; when it accepts 3 significant figures, either form earns the marks — just don't hand in a decimal where the exact value was demanded.
Two minus keys, boxes that hold the cursor, and a status bar that always tells you the mode: most Casio slips are caught by reading the screen you already have.
Before trusting any statistics or graph: check SET, check the selected functions, check the window.