Formulas and concepts, with worked examples
Sharpe ratio - (Portfolio return - risk-free rate) / standard deviation
Example: Return 9%, T-bills 3%, SD 12%: (9 - 3) / 12 = 0.50.
Current ratio / quick ratio - Current assets / current liabilities; (current assets - inventory) / current liabilities
Example: CA $500K, inventory $200K, CL $250K: current = 2.0; quick = 1.2.
Future value - PV x (1 + r)^n
Example: $10,000 at 6% for 10 years: 10,000 x 1.06^10 = $17,908.
Time-weighted vs. dollar-weighted - TWR removes the effect of client cash flows; DWR (IRR) includes them
Example: Judging a manager: use TWR. Judging the client’s own experience: DWR.
Numbers and deadlines to memorize
| Item | Number / rule | Source |
|---|---|---|
| Series 66 pass mark | 73 of 100 scored questions | |
| Exam format | 100 scored + 10 unscored, 150 minutes | |
| Weight of law and ethics | 45% (45 questions) | |
| Co-requisite for registration | Valid SIE and Series 7 | |
| 2026 IRA contribution limit | $7,500 ($1,100 catch-up at 50+) | |
| 2026 401(k) deferral limit | $24,500 | |
| Retest waits | 30 / 30 / 180 days; third-failure wait becomes 60 days on Jan 4, 2027 |
Download this Series 66 cheat sheet
The formulas, examples and numbers on this page as a printable one-pager (print or save as PDF) or a Word file.
Test yourself: 10 free Series 66 questions
Series 66 practice questions
Get the full Series 66 bank
Outline-weighted original questions with explanations, section drills and timed full-length exams. $99 one-time, 12 months, free access extension until you pass.
Frequently asked questions
Can I bring a cheat sheet into the Series 66?
No. Reference materials are not permitted in the testing session; this sheet is for studying only.
Is there a lot of math on the Series 66?
Some: statistics, ratios and time value of money, but law and ethics dominate.
Sources
- FINRA - Series 66 Uniform Combined State Law Exam (accessed 2026-09-23)
- IRS - 401(k) limit increases to $24,500 for 2026, IRA limit increases to $7,500 (accessed 2026-09-23)
- NASAA - Exam FAQs (accessed 2026-09-23)
- NASAA - Updated waiting period for Series 63, 65 and 66 retests (Aug 10, 2026) (accessed 2026-09-23)
- NASAA - Series 66 Test Specifications (effective June 12, 2023) (accessed 2026-09-23)