calculator
/kæl.kjə.leɪ.təɹ/noun
A machine, usually electronic, built to carry out mathematical calculations.
"Pocket calculator" is the classic phrase, though the pocket device has largely become a phone app.
Related words
compassAn instrument with a magnetized needle or electronic sensor that shows which way north is.highlighterA pen with bright, transparent ink used to mark important parts of a text.protractorA flat, usually half-circle instrument used to measure and draw angles.rulerA person who governs a country or holds power over others.backpackTo hike into remote country and camp overnight, carrying your gear in a pack on your back.eraserA small tool, usually made of rubber, used to rub out marks made with a pencil or pen.