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Image 1
The answer is 49.

What is the question?

Why does it work?
Image 2
The answer is 42.

What is the question?

Why does it work?
Image 3
The answer is 63.

What is the question?

Why does it work?
Image 4
The answer is 56.

What is the question?

Why does it work?

Does this always work?
Can you extend the method to other numbers?