456 + 44 + 300
= ( 456 + 44 ) + 300
= 500 + 300
= 800
123 + 123 + 123 + 123 = 123 x 4 = 492
789 + 789 + 789 + 567 = 2934
999 + 101 = 1000 + 100 = 1100
143 + 123 = 200 + 66 = 266