6. 408-270+21008:808 (31460+1040):(150-2400:120) 71370:234+695-50 (78213-75209)-207-45.308 280084:28-125-8 (992341:269+780)-325:5 (327+541350:450):3 434280:517-306+27449

Решение:

1. \( 408 - 270 + 21008 : 808 = 138 + 26 = 164 \)
2. \( (31460 + 1040) : (150 - 2400 : 120) = 32500 : (150 - 20) = 32500 : 130 = 250 \)
3. \( 71370 : 234 + 695 - 50 = 305 + 695 - 50 = 1000 - 50 = 950 \)
4. \( (78213 - 75209) - 207 - 45.308 = 3004 - 207 - 45.308 = 2797 - 45.308 = 2751.692 \)
5. \( 280084 : 28 - 125 - 8 = 10003 - 125 - 8 = 9870 - 8 = 9862 \)
6. \( (992341 : 269 + 780) - 325 : 5 = (3690 + 780) - 65 = 4470 - 65 = 4405 \)
7. \( (327 + 541350 : 450) : 3 = (327 + 1203) : 3 = 1530 : 3 = 510 \)
8. \( 434280 : 517 - 306 + 27449 = 840 - 306 + 27449 = 534 + 27449 = 27983 \)

Ответ: 164; 250; 950; 2751.692; 9862; 4405; 510; 27983.