Ключевые слова: background, balance, black, business, button, calculating, calculator, calculus, checkout, clicks, code, count, countdown, counter, customer, digits, display, equipment, figures, finance, gray, hand, industry, instrument, isolated, key, machine, mathematical, mathematics, measurement, metal, nobody, number, object, occupation, push, silver, single, small, sport, store, subtraction, tally, technology, voting, white,