📖 The Lesson
The GED gives you a TI-30XS calculator for most of the math section. Most students know how to add, subtract, multiply, and divide on it — but a handful of buttons get ignored entirely. Those are exactly the ones this lesson covers. Master these and you'll stop leaving points on the table.
The main point: The GED tests fractions and powers constantly. Entering them by hand and doing the arithmetic in your head is slow and error-prone. The calculator handles all of it — you just need to know which buttons to press.
Part 1 — The Fraction Button
Use \(\frac{n}{d}\) to enter any fraction.
The \(\frac{n}{d}\) button lets you enter fractions directly. Press the numerator first, then \(\frac{n}{d}\), then the denominator. The calculator displays it as a stacked fraction and treats it exactly like a fraction in all calculations.
Example — entering \(\frac{3}{4}\):
Press 3 \(\frac{n}{d}\) 4 and the display shows \(\frac{3}{4}\).
Example — adding \(\frac{1}{3}\) + \(\frac{1}{4}\):
Press 1 \(\frac{n}{d}\) 3 + 1 \(\frac{n}{d}\) 4 =
The calculator returns \(\frac{7}{12}\) — already in lowest terms. No common denominator work required.
Part 2 — The Conversion Button
Use ◄ ► to switch between fraction and decimal.
After you enter a fraction or get a fraction as a result, press ◄ ► to toggle between the fraction and its decimal equivalent. This is useful when an answer choice is a decimal but your calculator is showing a fraction — or vice versa.
Example:
Enter 3 \(\frac{n}{d}\) 4, then press ◄ ►
Display switches from \(\frac{3}{4}\) to 0.75
Press ◄ ► again and it flips back to \(\frac{3}{4}\). Use this any time you need to match the format of an answer choice.
Here are the power and root buttons. These show up constantly in geometry — area of squares, right triangles, and the Pythagorean theorem.
Square — x²
Number, then x²
Enter the number first, then press x².
5² = 25:
Press 5 x² = → 25
\(\frac{2}{5}\)² = \(\frac{4}{25}\):
Press 2 \(\frac{n}{d}\) 5 x² = → \(\frac{4}{25}\)
Square Root — √
2nd then x²
Square root is the second function on the x² key. Press 2nd first, then x², then the number.
√49 = 7:
Press 2nd x² 4 9 = → 7
√2 ≈ 1.41:
Same steps → 1.4142…
Cube — x³
Number, then ^ 3
There's no dedicated cube button. Use the caret ^ (exponent key) with 3.
4³ = 64:
Press 4 ^ 3 = → 64
This works for any exponent — just change the 3 to whatever power you need.
Cube Root — ∛
3 then 2nd then ^ then number
Enter the index 3 first, then press 2nd, then the ^ key, then the number under the radical, then ENTER.
∛125 = 5:
Press 3 2nd ^ 1 2 5 ENTER → 5
∛8 = 2:
Press 3 2nd ^ 8 ENTER → 2
To get a decimal result:
After pressing ENTER, press ◄ ► then ENTER again to convert.
| What you want |
Keystrokes |
Example |
| Enter a fraction |
n \(\frac{n}{d}\) d |
\(\frac{3}{4}\) → 3 \(\frac{n}{d}\) 4 |
| Convert fraction ↔ decimal |
◄ ► |
\(\frac{1}{2}\) ↔ 0.5 |
| Square a number |
n x² |
6² → 6 x² = 36 |
| Square root |
2nd x² n |
√81 → 9 |
| Cube a number |
n ^ 3 |
3³ → 3 ^ 3 = 27 |
| Cube root |
3 2nd ^ n ENTER |
∛64 → 3 2nd ^ 6 4 ENTER = 4 |
The takeaway: You don't need to memorize square roots or cube roots — the calculator handles them. What you do need to know is which buttons to press. Practice entering a few fractions like \(\frac{2}{5}\) and \(\frac{7}{10}\) until it feels automatic, and get comfortable using ◄ ► to switch formats.
🔢 Worked Examples
Example 1 — Fraction addition
Simplify: ½ + ¼
Press: 1 [n/d] 2 [+] 1 [n/d] 4 [=]
Calculator shows: 3/4
Answer: 3/4
Example 2 — Square and square root
The area of a square is 144 cm². What is the side length?
A = s²
144 = s²
s = √144
Press: [2nd] [x²] 1 4 4 [=]
s = 12 cm
Example 3 — Cube root
A cube has a volume of 216 cm³. What is the side length?
V = s³
216 = s³
s = ³√216
Press: 3 [2nd] [^] 2 1 6 [ENTER]
s = 6 cm
Reference
GED Formula Sheet
All formulas available on the real test — opens in a new tab
📋 Open Formula Sheet
✏️ Practice Questions
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Negative Numbers
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