【5】In the six-digit number 123487, insert a digit identical to one of its digits right after that digit, to form a seven-digit number. Among all these seven-digit numbers, the largest one is ( ).

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【Key Points】Digital problems, Extreme value problems.
【Analysis】1123487, 1223487, 1233487, 1234487, 1234887, 1234877, so the largest one is 1234887.

【Answer】1234887