Ключевые слова: account, accounting, add, addition, background, balance, bank, black, business, button, calculate, calculation, calculator, count, design, digital, display, divide, division, economy, education, electronic, equipment, finance, financial, gray, isolated, keyboard, keypad, math, mathematical, mathematics, multiply, nobody, number, object, office, plastic, red, school, shiny, sign, silver, single, subtraction, sum, symbol, technology, white, work,