Number theoryDifficulty 3.0AMC 10/12Find the answerUnited Kingdom
Amrita needs to select a new PIN. She decides it will be made up of four non-zero digits with the following properties: i) The first two digits and the last two digits each make up a two-digit number which is a multiple of 11. ii) The sum of all the digits is a multiple of 11. How many different possibilities are there for Amrita's PIN?
(A) 1 (B) 2 (C) 4 (D) 8 (E) 16
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