1) 152 + 343 = 495;
2) 492 + 108 + 17 = 600 + 17 = 617;
3) 513 + 85 + 87 = (513 + 87) + 85 = 600 + 85 = 685;
4) 120 + 546 + 880 = (120 + 880) + 546 = 1000 + 546 = 1546;
5) 32 + 14 + 18 + 16 = (32 + 18) + (14 + 16) = 50 + 30 = 80;
6) 76 + 21 + 79 + 4 = (76 + 4) + (21 + 79) = 80 + 100 = 180.