Worksheet is asking you for the numbers and tell you where they are placed.
Across:
1: 123
4: 354
6: 789
7: 926
9: 496
11: 351
13:435
15:872
17:503
19: 214
20: 914
21: 37
22: 479
Down:
1: 187
2: 339
5: 492
8: 653
10: 999 - 15 = 984
12: 137
14:554
15:864
16:213
18:397
21:352