Isabel is thinking of an even number between 234 and 250. The sum of the digits is double the digit in the ones place. What is Isabel's number?

Since the required number is between 234 and 250, then the first digit of the number is 2 and the second digit can either be 3 or 4.

Let the second and the third digits be x and y respectively, then

2 + x + y = 2y

Consider when the second digit is 3, then

2 + 3 + y = 2y

5 = y

Thus, the number is 235.

Similarly, consider when the second digit is 4, then

2 + 4 + y = 2y

6 = y

Thus, the number is 246.

Since the required number is an even number, therefore, Isabel's number is 246.