The number 444444 is divisible by which of the following?
Answer: D
A number formed by repeating a digit 6 times is always divisible by 3, 7, 11, and 13. This is because such a number is a multiple of 111111, and \(111111 = 3 \times 7 \times 11 \times 13 \times 37\). Let's check for this specific number. Divisibility by 3: sum of digits = 24 (divisible). Divisibility by 11: (4+4+4)-(4+4+4)=0 (divisible). Divisibility by 7 and 13: This is a property of such numbers. The number is 4 x 111111, so it is divisible by all prime factors of 111111.