Breaking Numbers Apart: Mental Math for Case Interviews
Breaking Numbers Apart
What does “breaking numbers apart” mean in mental math? It means decomposing a number into its place values (like 268 = 200 + 60 + 8) to simplify calculations. This technique is essential for fast, accurate math in consulting case interviews — especially for market sizing, revenue math, and operational metrics.
Core Concept: Why This Technique Matters
Breaking numbers apart transforms complex calculations into simple, manageable steps by splitting numbers by place value.
- Calculate total revenue across multiple units or locations
- Estimate market sizes by segment
- Perform quick cost or margin analyses under time pressure
268 = 200 + 60 + 8
How to Use It: Step-by-Step with Addition
Let’s walk through a detailed example: 268 + 157
Break the numbers apart
268 = 200 + 60 + 8; 157 = 100 + 50 + 7
Add like terms
(200 + 100) + (60 + 50) + (8 + 7) = 300 + 110 + 15
Combine results
300 + 110 = 410 → 410 + 15 = 425
✅ Answer: 268 + 157 = 425
Real-World Consulting Application
This isn’t just academic—it’s used daily in case interviews and real consulting work.
Example: Monthly revenue — 24 × $13,000 = (20 + 4) × $13,000 = $260,000 + $52,000 = $312,000
Ready to Drill This Skill?
Reading is not enough. To make breaking numbers apart automatic under pressure, you need timed, focused practice.
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