Number TheoryLevel 4 · Challenge
Consider all positive four-digit integers consisting of only even digits. What fraction of these integers are divisible by 4?
- A. 1/4
- B. 2/5
- C. 1/2
- D. 3/5
- E. 3/4
Work through 2026 AMC 8 Problem 16 on divisibility with a written solution, hints, and a visual explanation.
Consider all positive four-digit integers consisting of only even digits. What fraction of these integers are divisible by 4?
Answer: D · 3/5
A number is divisible by 4 if its last two digits form a number divisible by 4. Since all digits must be even (0, 2, 4, 6, 8), the first two digits don't affect divisibility by 4.
Since the tens digit is always even, divisibility by 4 depends only on the ones digit. Of the 5 even digits {0, 2, 4, 6, 8}, exactly 3 (namely 0, 4, 8) make the last two digits divisible by 4.
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