When did Thomas Edison invent the electric calculator?

Answer 1

He never did. Indeed, Edison did not do any work with electric calculators.

Others invented mechanical devices that could do calculations, but these were (literally) one of a kind. Not until 1851 was a calculator sold on a large-scale basis, and even then only a few thousand were sold in the next half century.

Note that, the item "Edison Cordless Calculator Patent 1902" is a joke item from the 1960s that only uses that name and date for humor.