Brain Teasers & Mental Math
Estimate the number of streetlights in a city of 1 million people.
Model answer
Bottom-up by road network. A city of ~1M might cover ~300 sq miles. Assume road density giving ~1,500 miles of lit roadway. Streetlights are spaced ~150 ft apart → ~35 lights/mile → 1,500 × 35 ≈…
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