Problem 14 · 1987 AJHSME
Hard
Ratios, Rates & Proportions
unit-conversion
A computer can do 10,000 additions per second. How many additions can it do in one hour?
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Answer: B — 36 million.
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Hint 1 of 2
The rate is per second but the question asks per hour. How many seconds are hiding inside one hour?
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Hint 2 of 2
Convert the time, not the rate: 1 hour = 60 minutes × 60 seconds = 3600 seconds. Then it's one multiplication.
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Approach: convert the time unit, then multiply
- One hour = 60 × 60 = 3600 seconds. At 10,000 additions each second, that's 10,000 × 3600 = 36,000,000 = 36 million.
- Quick way to multiply: 10,000 × 3600 = (10,000 × 36) × 100 = 360,000 × 100 = 36,000,000.
- Trap-check: 6 million uses 600 seconds (a wrong minute count) and 60 million uses 6000. Getting the 3600 right is the whole problem.
Mark:
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