520 + 80 = 600
970 - 160 = 810
1000 - 900 = 100
630 + 400 = 1030
250 ⋅ 3 = 750
400 ⋅ 5 = 2000
14 ⋅ 7 = 98
90 ⋅ 30 = 2700
Ответ: 600, 810, 100, 1030, 750, 2000, 98, 2700