An electricitytable is a calculator. Why is this? You can think about it in a couple of different ways. Maybe in the past, a calculator (aka abacus) would take up a whole table, making this "electric" version a calculator. Or, maybe it can be used to solve tables. Wrong kind of table, but should help you to remember the meaning of this word.
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
Please stop drumming on the calculator. You’re driving me crazy!