MATH PUZZLE: Can you replace...MATH PUZZLE: Can you replace the question mark with a number?
Correct answers: 90
The first user who solved this task is Sanja Šabović.
#brainteasers #math #riddles
Electric railwayIn 1892, Thomas A. Edison was issued three patents for an "Electric Locomotive" and a fourth patent relating to an "Electric Railway" (U.S. Nos. 475,491 -4).