The correct answer is option (D):
63
Let the single-digit number be x. We are given that when x is multiplied by 1234, the units digit and the thousands digit of the product are the same. We can write this as:
x * 1234 = Product.
Let's test each possible value of x from 1 to 9.
If x = 1: 1 * 1234 = 1234. Units digit is 4, thousands digit is 1. Not the same.
If x = 2: 2 * 1234 = 2468. Units digit is 8, thousands digit is 2. Not the same.
If x = 3: 3 * 1234 = 3702. Units digit is 2, thousands digit is 3. Not the same.
If x = 4: 4 * 1234 = 4936. Units digit is 6, thousands digit is 4. Not the same.
If x = 5: 5 * 1234 = 6170. Units digit is 0, thousands digit is 6. Not the same.
If x = 6: 6 * 1234 = 7404. Units digit is 4, thousands digit is 7. Not the same.
If x = 7: 7 * 1234 = 8638. Units digit is 8, thousands digit is 8. This is correct.
Therefore, x = 7. The product is 8638. The units digit is 8 and the thousands digit is 8, which are the same. The number formed by the other two digits in order is 63.
Thus, the answer is 63.