šŸ’”
Learning My Way
Tutoring with a Twist
šŸ“… Exam
4 to 5 Nov 2026
Home ā€ŗ Calculator Skills
šŸ§® Casio scientific Ā· fx-82AU / fx-100AU

šŸ§® Calculator Skills

The exam lets you use your calculator, so let it do the heavy lifting. There are only a handful of button sequences that come up again and again. Learn these and you stop doing finance by hand.

Which calculator is this for?

These steps are for a Casio scientific (the standard General Maths calculator, like the fx-82AU PLUS II or fx-100AU PLUS). The buttons are the same on both, with one exception flagged in the correlation section.

Got a ClassPad or a TI? The ideas are identical but the menus differ, so check with Nat.

ā­ The golden rule: keep the full number on your calculator the whole way through and only round the final answer. The Ans key remembers the full value for you, decimals and all. Rounding early is the most common way to get a finance answer marked wrong.
1
The three buttons people get wrong

Tiny things that cause "ERROR" or a wrong answer:

Negative numbers use the (āˆ’) key, not the subtract key

To type negative 400, press (āˆ’) then 400. The big āˆ’ key is only for subtracting one thing from another.

Brackets when you need an add or subtract to happen first

The calculator always does Ɨ and Ć· before + and āˆ’. So for 5000 Ɨ (1 + 0.06) you must use brackets, or it does 5000 Ɨ 1 first and adds 0.06 after.

The Sā‡”D key turns a fraction answer into a decimal

If the screen shows a fraction and you wanted a decimal (for money), press Sā‡”D to flip it.

2
Build a loan or savings table fast (the Ans trick)

This is the big one for finance. Instead of retyping the balance every line, the Ans key feeds the last answer straight back in. One press of = steps forward one period.

Example: Vā‚ = 1000, grows Ɨ1.1 each year, then add 500

  1. Type the starting balance, then equals:
    1000=
    The screen now holds 1000 as "Ans".
  2. Type the rule using the Ans key, then equals:
    1.1ƗAns+500=
    Screen shows 1600. That is Vā‚‚.
  3. Now just keep pressing equals. Each press is one more year:
    =ā†’ 2260   =ā†’ 2986   =ā†’ ...
    Count your presses. 12 presses after step 2 gives the balance after 12 payments.
šŸ’” Loans work the same, just with a minus. For a repayment you subtract instead of add. Example for a loan growing 5% then paying 400 back: 1.05ƗAnsāˆ’400=, then keep pressing equals to watch the loan shrink.
Watch for: if you press = one too many times, you have gone a period too far. Just note which press matches which period as you go (a quick tally on paper saves you).
3
Correlation r and the regression line
Read this first: the basic fx-82AU PLUS II cannot calculate r or the regression line. If that is Josh's calculator, that is okay: in the exam the value of r and the equation are given to you, and the skill is reading and using them. The steps below are for the fx-100AU PLUS (and other models that have "A+BX" in the stats menu).

Getting r, and the line y = A + Bx

  1. Go into stats mode and pick linear:
    MODEā†’STATā†’A+BX
    "A+BX" is the linear regression option.
  2. Type the x values down the X column, pressing = after each. Then arrow across to the Y column and type the y values the same way.
  3. Press AC to finish entering data (this does not delete it).
  4. Open the stats results menu and choose Reg:
    SHIFT1ā†’Reg
    Pick A, B, or r and press = to display it.
A = 4.21   (the y-intercept)
B = 2.58   (the gradient)
r = 0.97   (the correlation)

So the line is y = 4.21 + 2.58x and the correlation is strong and positive. Always write the line with the real variable names where the question gives them.

4
Compound interest with the power key

For "after 25 years" questions you do not want 300 button presses. Use the formula with the power key xā–¢ (it looks like x with a small raised box).

Example: $5000 at 6% per year for 10 years

Formula: A = 5000 Ɨ (1 + 0.06)10

5000Ɨ(1+0.06)xā–¢10=
8954.2380...   round LAST ā†’ $8954.24
The bracket is essential. Without it the calculator reads 5000 Ɨ 1, then adds 0.06 to the power, which is nonsense. Brackets around (1 + 0.06) every time.
šŸ–Øļø Tip for Nat: print this page and slot it in the front of Josh's binder next to the formula sheet. Pair it live in a session: you read the keys, he presses them, until the Ans trick is muscle memory.