458 + 333 + 42 + 67 = (458 + 42) + (333 + 67) = 500 + 400 = 900

635 + 308 + 1365 + 392 = (635 + 1365) + (308 + 392) = 2000 + 700 = 2700

411 + 419 + 145 + 725 + 87 = (411 + 419) + (145 + 725) + 87 = 830 + 870 + 87 = 1787

11 + 12 + 13 + 14 + 15 + 16 + 17 + 18 + 19 = (11 + 19) + (12 + 18) + (13 + 17) + (14 + 16) + 15 = 30 + 30 + 30 + 30 + 15 = 135