23.

13 806 : 531 = 26

30 240 : 420 = 72

7 009 * 24 = 168 216

5 060 * 73 = 369 380

1000 - 100 : 5 * (2 + 8) = 1000 - 20 * 10 = 1000 - 200 = 800

1000 - (100 : 5 * 2 + 8) = 1000 - (20 * 2 + 8) = 1000 - (40 + 8) = 1000 - 48 = 952