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What are the missing numbers in the pyramids?

Top-heavy Pyramids

Stage: 3 Challenge Level: Challenge Level:3 Challenge Level:3 Challenge Level:3

Order the numbers in a variety of ways. Where a number is placed does make a difference.

Look at the first example given. How many times is the 4 used in an addition calculation in the pyramid? What about the 5? And the 7?
Try this with the second example too.
Would it help to make up some larger pyramids and then to repeat this process?
Do you notice a pattern? Could this help?