Question 1 A. Do 23 times 2 times 2. This will give you the same answer as if you were to use 4.
Question 1 B. Use 10 times 2 plus the number in the ones place, then multiply them together.
Question 2. There would be an average of 40 student per bus, therefore, there will be 10 buses, and 40 students in each bus.
Question 3. You could put 12 counters in: 6 groups of 2, 2 groups of 6, 4 groups of 3, or 3 groups of 4. (I think there's more but that's all I can think of. Hope you got the memo)
Hope this helped! :D