Replace the question mark with a number
MATH PUZZLE: Can you replace the question mark with a number?Correct answers: 490
The first user who solved this task is Vladimir Krnac.
#brainteasers #math #riddles
SteamboatIn 1803, a patent was issued for the engine used on a twin-screw propeller steamboat built by John Stevens of Hoboken, N.Y. in the same year. The engine was a double direct-acting noncondensing engine with a 4.5-inch cylinder and 9-inch stroke. The boat was 25-feet-long and four-feet wide, with two 5-foot screw propellers with four blades set at an angle of 35º. It successfully navigated in New York Harbor in 1804. Stevens also developed the first sea-going steamship, initiated regular ferry service from New Jersey to New York, and designed and built the first American steam locomotive. In addition, he proposed a vehicular tunnel under the Hudson River, and the use of an elevated railroad in New York City.* |