Cyfer.

Train Your Thinking.

Practice Library

5 Sections · Levels 1–5

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Practice Library

Section 1 — Mental Arithmetic

Divisions, Multiplications & Percentages

Pure mental speed drills · Levels 1–5

Fast arithmetic you can do in your head. Start with small numbers (L1) and work up to large-scale mental calculations (L5). No pen needed.

Section 2 — Business Math

Market Math, Break Evens & Growth

Market sizing · Break-even · Time series · Levels 1–5

Business calculations with clean, manageable numbers. Levels 1–3 are mental. Levels 4–5 are harder — use pen and paper if needed.

Section 3 — Consulting Math

Profitability, Market Entry, Growth & Pricing

Case-ready formulas · Levels 1–5

The 20 key metrics every consultant needs cold. Levels 1–3: mental. Levels 4–5: pen & paper recommended. Covers profit, margins, ROI, NPV, CAGR, market share & pricing.

Section 4 — Everyday Life

Tips, Discounts, Shopping & Life

Real-world mental math · Levels 1–5

Grocery bills, restaurant tips, discounts, fuel, splitting bills — the mental math you actually use every day.

Section 5 — Case Math

Structured Case Math

Frame · Calculate · Interpret · 4 archetypes

MBB-style case math in context. Each question has three steps: frame the problem, calculate, then interpret the result as a consultant would. Directly trains the gap between knowing the math and knowing what it means.

Case Math

Frame · Calculate · Interpret

Each question arrives as a real business situation. Frame the problem, calculate, then interpret the result as a consultant would.

Choose an archetype

Profitability

Revenue · Costs · Margins · Most common first case

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Market Entry & Sizing

TAM · Segmentation · Penetration · Share

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Investment & Growth

M&A · Payback · CAGR · Synergies

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Operations & Cost

Capacity · Efficiency · Cost reduction · Make vs buy

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Mixed — Exam Mode

Random archetype · Full case pressure

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Profitability

Question 1 of 6

STEP 1

Frame the problem first:

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