A year lasts 31,000,000 seconds. Which expression is in scientific notation and gives the number of seconds in a thousand years? 31,000,000 × 10 3 3.1 × 10 7 × 10 3 = 3.1 × 10 4 3.1 × 10 7 × 10 3 = 3.1 × 10 10 31 million × 10 3