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CORTIX

Math Dojo

Method · Hub

20+ mental-math drills. Each drill teaches one technique. Pick a family below.

Reference

📚 Quant Cheat Sheet
The 30 facts every interview candidate should know cold — one-page reference.
📈 Greeks Explorer Visualization
Drag sliders. Watch hedge sensitivities reshape in real time.

Mixed & Sprints

🎲 Math Mix
Cycle through every dojo skill in one 90-second sprint.
⚡ Arithmetic Sprint
Rapid-fire mental arithmetic. Timed.
⏱ 35 in 3
Speed-math sprint — 35 questions, 3 minutes.
🔥 80 in 8
The full mental-math gauntlet — 80 questions, 8 minutes.

Addition & Subtraction

➖ Subtract from 1000
Complement subtraction — nines and a ten.
💲 Tens Match
Same-tens, units-to-10 trick for fast products.

Multiplication

✅ Multiply by 11
Master the classic 11x add-the-neighbours trick.
✕ 2×2 Multiply
Two-digit by two-digit multiplication, the cross-method way.
🔁 Doubling & Halving
Reshape products into easier ones.
📐 Difference of Squares
Symmetric products around a midpoint — (a-d)(a+d).
🎯 Power Multiply
Multiply with exponent shortcuts.

Squaring & Powers

⬜ Squaring Spree
Square two- and three-digit numbers mentally.
Σ Sum of Powers
Σn, Σn², Σn³ closed forms.

Division & Divisibility

➗ Mental Division
Division shortcuts — round, rescale, refine.
✔ Divisibility Tests
Yes/no divisibility — six rules, fast.
📋 Casting Out Nines
Mod-9 verification — spot-check arithmetic.

Percentages & Growth

📈 Percentage Flip
x% of y = y% of x — reverse percentage tricks.
📊 Rule of 70
Doubling time ≈ 70 / r% — growth approximation.

Estimation & Geometry

📐 Hypotenuse
Right-triangle hypotenuse from two legs — fast approximation.
🔢 Order of Magnitude
Digit count of a×b via log10 — rough sizing.

Logic & Memory

📅 Doomsday
Day of the week for any date — Conway's algorithm.
🧠 Advanced Calc
Higher-level computation drills.
🧮 Algebra & Logic
Equations and reasoning prompts.
Independent · Legal