Combinatorics · Counting digit strings · Divisibility by 4 · Multiplication principle · Residues mod 4
Problem 5, 2004
← Prev · 33 / 33 · Next →How many integers \(n\) with \(10 \le n < 100000\) are divisible by \(4\), contain no digit \(0\) in their decimal representation, and have no two adjacent digits equal?
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Serbian Republic Competition (Republicko takmicenje) 2004, high school grade I, category A, problem 5. Organized by the Mathematical Society of Serbia (DMS). Source