The tree
So, there is a mysterious tree. You need to figure out how many branches it has for some reason.
Unfortunately, the tree has been cut down. But, one person saw the tree before it was cut down. He doesn't remember how many branches there was. But, he remembers some clues.
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The number of branches is between 1 and 874 inclusive.
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The number of branches is prime.
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The number is a palindrome. (the same backwards and forwards)
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The number's 1st digit and the 2nd digit's difference is 2.
Can you figure out the number of branches?
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at first,the number is a palindrome.so, 5 3 5 , 6 5 6 , 7 5 7 are in the race.
secondly,the number is a prime number.that eliminates 535 & 656
so,their remains only 7 5 7