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there. I came across a number pattern problem like the one in the following picture. Does anyone happen to know what the ? stands for? Or how can we calculate the number? Thank you. enter image description here

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The third number in each sequence is the sum of the squares of the previous 2. $$2^2+6^2=4+36=40$$ $$3^2+7^2=9+49=58$$ $$6^2+5^2=36+25=61$$

Using this rule, we can do it for the missing number: $$2^2+3^2=4+9=13$$

So the correct answer is (A) 13

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