Ключевые слова: 2, 3, 4, 5, 6, 7, 8, 9, abstract, amount, background, banner, blackboard, blank, blankness, board, calculate, chalk, chalkboard, child, children, cipher, classroom, compute, consideration, count, cypher, design, digit, digital, digits1, education, enlighten, enlightenment, figure, flat, glass, grunge, icon, infant, label, lacunae, math, mathematics, number, numeral, numeric, pattern, plank, planning, preschool, primary, school, schoolroom, tag, teaching, texture, write,