Вправи 501 - 600 » 539

Обчисли зручним способом. 639 + (61 + 37) = (639 + 61) + 37 = 700 + 37 = 737 357 + 291 + 43 = (357 + 43) + 291 = 400 + 291 = 691 581 + 284 + 19 = (581 + 19) + 284 = 600 + 284 = 884 (492 + 43) + 8 = (492 + 8) + 43 = 500 + 43 = 543 648 + 125 + 75 = 648 + (125 + 75) = 648 + 200 = 848 (123 + 123) + 77 = 123 + (123 + 77) = 123 + 200 = 323