all two-digit numbers whose units digits is half the tens digit?

To find all two-digit numbers whose unit digit is half the tens digit, we can break down the problem into steps:

1. Start by listing all possible tens digits.
- The tens digit can range from 1 to 9 since we are looking for two-digit numbers.
- So, let's list the possible tens digits: 1, 2, 3, 4, 5, 6, 7, 8, 9.

2. Determine the corresponding unit digit for each tens digit.
- The unit digit should be half the value of the corresponding tens digit.
- For example, if the tens digit is 1, the unit digit should be 1/2, which is 0.5. However, since we are dealing with whole numbers, we need to round this down to the nearest whole number, which is 0. Therefore, for a tens digit of 1, the unit digit is 0.
- Continue this process for all the possible tens digits.

3. Combine the tens and unit digits to form the two-digit numbers.
- Combine each tens digit with its corresponding calculated unit digit from step 2.
- For example, for a tens digit of 1 and a unit digit of 0, the two-digit number is 10.
- Repeat this step for all the possible tens digits.

By following these steps, you can find all the two-digit numbers whose unit digit is half the tens digit: 10, 21, 32, 43, 54, 65, 76, 87, 98.