Mental Math and Calculation Speed Questions

Build fluency with percentage calculations (15% of 400M, growth rates, margins), division operations (average calculations, per-unit metrics), and basic algebra. Practice scenarios: 'If gross margin is 40% and revenue is $500M, what's gross profit?' or 'If net income is $50M on revenue of $1B, what's the net margin?' Build speed to solve these in 10-20 seconds without a calculator. Use a calculator for verification but develop mental capability.