Your calculator is your most important tool on the PE exam. While Excel isn't allowed on exam day, practicing with Excel formulas helps you understand the math. This guide shows you how to maximize your TI-36X Pro efficiency and how Excel practice translates to faster exam calculations.
Practice the formulas - Our calculator shows both the result AND the Excel formula
Try the CalculatorNCEES Approved Calculators
Before we dive into tips, make sure you have an approved calculator:
| Calculator | Pros | Best For |
|---|---|---|
| TI-36X Pro | Most features, multi-line display, equation solver | Most PE disciplines |
| TI-30X IIS | Simple, reliable, dual-line | Basic calculations |
| Casio FX-115ES Plus | Natural textbook display, matrix functions | Structural, complex math |
| HP 35s | RPN mode, programming | Experienced RPN users |
TI-36X Pro Essential Tips
1Use the ANS Key for Chain Calculations
The ANS key stores your last result. Instead of writing down intermediate values, chain your calculations:
Then: ANS × 8 ENTER → gives Q = V × A
This eliminates copying errors and saves time.
2Store Constants in Memory
The TI-36X Pro has memory slots A-D. Store frequently used values at the start of each exam section:
Store: 449 STO B (gpm to cfs)
Store: 3960 STO C (pump HP)
Recall: RCL A
3Master the Exponent Key
Many equations use fractional exponents. Practice these common patterns:
S^(1/2): S ^ 0.5 ENTER (or use √ key)
C^1.852: C ^ 1.852 ENTER
4Use MathPrint Mode
The TI-36X Pro can display fractions and exponents like a textbook:
This makes it easier to verify you've entered complex equations correctly.
5The Numeric Solver
For equations that are difficult to solve algebraically (like Colebrook), use the numeric solver:
Enter equation (e.g., x^2 - 5x + 6 = 0)
Enter initial guess
ENTER to solve
How Excel Practice Helps
Even though you can't use Excel on the exam, practicing with Excel formulas provides key benefits:
1. Understanding Formula Structure
When you see an Excel formula like:
You understand the order of operations and can replicate it on your calculator.
2. Verification During Study
Build an Excel spreadsheet to verify your calculator answers. If they don't match, you know you made a mistake somewhere.
3. Unit Conversion Practice
Excel formulas often have built-in unit conversions. Study these to understand what conversions are needed:
B2/448.83→ gpm to cfsB3/12→ inches to feet*8.34→ mg/L × MGD to lbs/day
Calculator Keystroke Examples
Manning's Equation (V = 1.486/n × R^(2/3) × S^(1/2))
Given: n = 0.013, R = 1.5 ft, S = 0.002
Result: 6.68 ft/s
Hazen-Williams Head Loss
Given: L = 1000 ft, Q = 500 gpm, C = 130, D = 6 in
Result: 21.4 ft
Pump Horsepower
Given: Q = 500 gpm, TDH = 75 ft
Result: 9.47 HP (water horsepower)
Common Calculator Mistakes to Avoid
- Forgetting parentheses: 1/2×3 ≠ 1/(2×3). Use parentheses liberally.
- Wrong angle mode: Check DEG vs RAD before any trig calculations.
- Clearing too much: Use CE to clear just the entry, not AC which clears everything.
- Not using ANS: Retyping long numbers introduces errors.
- Forgetting unit conversions: The formula is right but units are wrong.
Pre-Exam Calculator Checklist
- Fresh batteries (bring backup)
- Practice with YOUR calculator for at least 50 hours
- Memorize key constants (8.34, 449, 1.486, 3960)
- Know how to access all functions without looking
- Verify your calculator is on the NCEES approved list
- Bring a backup approved calculator
Practice with Excel + Calculator - See both the formula and the result
Start Practicing