The smallest two-digit number that is not the sum of three different one-digit numbers isA. 10B. 15C. 23D. 25E. 28

To solve this problem, we need to understand that any two-digit number can be the sum of three different one-digit numbers.

Step 1: Start with the smallest two-digit number, which is 10.

Step 2: Check if it can be the sum of three different one-digit numbers. The smallest three different one-digit numbers are 1, 2, and 3. Their sum is 6, which is less than 10. So, 10 can be the sum of three different one-digit numbers.

Step 3: Move to the next smallest two-digit number, which is 11. Repeat the process. The sum of 1, 2, and 3 is still less than 11. So, 11 can also be the sum of three different one-digit numbers.

Step 4: Continue this process until you find a two-digit number that cannot be the sum of three different one-digit numbers.

Step 5: After checking, you will find that the smallest two-digit number that cannot be the sum of three different one-digit numbers is 15.

So, the answer is B. 15.

To solve this problem, we need to understand that a one-digit number ranges from 0 to 9.

Step 1: Start by considering the smallest two-digit number, which is 10. Can it be expressed as the sum of three different one-digit numbers? Yes, it can. For example, 1 + 2 + 7 = 10.

Step 2: Move to the next smallest two-digit number, which is 11. Can it be expressed as the sum of three different one-digit numbers? Yes, it can. For example, 1 + 3 + 7 = 11.

Step 3: Continue this process with the next smallest two-digit numbers. You will find that all numbers up to 23 can be expressed as the sum of three different one-digit numbers.

Step 4: When you reach 24, you will find that it can also be expressed as the sum of three different one-digit numbers. For example, 9 + 8 + 7 = 24.

Step 5: However, when you reach 25, you will find that it cannot be expressed as the sum of three different one-digit numbers. This is because the largest sum you can get from three different one-digit numbers is 9 + 8 + 7 = 24.

Therefore, the smallest two-digit number that is not the sum of three different one-digit numbers is 25. So, the answer is D. 25.

To solve this problem, we need to understand that the maximum sum we can get from three different one-digit numbers is 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 = 45.

Now, let's start from the smallest two-digit number, which is 10, and see if we can express it as the sum of three different one-digit numbers.

10 can be expressed as 1 + 2 + 7, 1 + 3 + 6, 1 + 4 + 5, 2 + 3 + 5, and so on.

Next, let's try 15. It can be expressed as 1 + 5 + 9, 1 + 6 + 8, 2 + 4 + 9, 2 + 5 + 8, and so on.

Next, let's try 23. It can be expressed as 1 + 8 + 9, 2 + 7 + 9, 3 + 7 + 8, and so on.

Next, let's try 25. It can be expressed as 1 + 9 + 9, 2 + 8 + 9, 3 + 7 + 9, and so on.

Finally, let's try 28. It cannot be expressed as the sum of three different one-digit numbers because the maximum sum we can get from three different one-digit numbers is 9 + 8 + 7 = 24.

Therefore, the smallest two-digit number that is not the sum of three different one-digit numbers is 28. So, the answer is E. 28.

To solve this problem, we need to understand that any two-digit number can be the sum of three different one-digit numbers.

Step 1: Start with the smallest two-digit number, which is 10.

Step 2: Check if it can be the sum of three different one-digit numbers. The smallest three different one-digit numbers are 1, 2, and 3. Their sum is 6, which is less than 10. So, 10 can be the sum of three different one-digit numbers.

Step 3: Move to the next smallest two-digit number, which is 11. Repeat the process. The sum of 1, 2, and 3 is still less than 11. So, 11 can also be the sum of three different one-digit numbers.

Step 4: Continue this process until you find a two-digit number that cannot be the sum of three different one-digit numbers.

Step 5: After checking, you will find that the smallest two-digit number that cannot be the sum of three different one-digit numbers is 15.

So, the answer is B. 15.

To solve this problem, we need to understand that the maximum sum we can get from three different one-digit numbers is 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 = 45.

Now, let's start from the smallest two-digit number, which is 10, and see if we can express it as the sum of three different one-digit numbers.

10 can be expressed as 1 + 2 + 7, or 1 + 3 + 6, or 1 + 4 + 5, etc.

Next, let's try 15.

15 can be expressed as 1 + 5 + 9, or 2 + 4 + 9, or 2 + 5 + 8, etc.

Next, let's try 23.

23 can be expressed as 9 + 8 + 6, or 9 + 7 + 7, but the numbers are not different.

So, the smallest two-digit number that is not the sum of three different one-digit numbers is 23.

Therefore, the answer is C. 23.

To solve this problem, we need to understand that a one-digit number ranges from 0 to 9.

Step 1: Start by considering the smallest three different one-digit numbers, which are 0, 1, and 2. Their sum is 3.

Step 2: Increase the numbers gradually while ensuring they are different. The next set would be 0, 1, and 3, which sum up to 4.

Step 3: Continue this process. You will find that you can create all numbers from 3 to 17 using a combination of three different one-digit numbers.

Step 4: However, when you try to create 18, you will find it impossible because the three largest one-digit numbers (7, 8, and 9) only sum up to 24.

Step 5: Therefore, the smallest two-digit number that cannot be the sum of three different one-digit numbers is 18.

However, 18 is not an option in the choices given. This means there might be a mistake in the question or the options provided.

To solve this problem, we need to understand that any two-digit number can be the sum of three different one-digit numbers.

Step 1: Start with the smallest two-digit number, which is 10.

Step 2: Check if it can be the sum of three different one-digit numbers. The smallest three different one-digit numbers are 1, 2, and 3. Their sum is 6, which is less than 10. So, 10 can be the sum of three different one-digit numbers.

Step 3: Move to the next smallest two-digit number, which is 11. Repeat the process. The sum of 1, 2, and 3 is still less than 11. So, 11 can also be the sum of three different one-digit numbers.

Step 4: Continue this process until you find a two-digit number that cannot be the sum of three different one-digit numbers.

Step 5: After checking, you will find that the smallest two-digit number that cannot be the sum of three different one-digit numbers is 15.

So, the answer is B. 15.

To solve this problem, we need to understand that the maximum sum we can get from three different one-digit numbers is 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 = 45.

Now, let's start from the smallest two-digit number, which is 10, and see if we can express it as the sum of three different one-digit numbers.

10 can be expressed as 1 + 2 + 7, or 1 + 3 + 6, or 1 + 4 + 5, etc.

Next, let's try 15.

15 can be expressed as 1 + 5 + 9, or 2 + 4 + 9, or 2 + 5 + 8, etc.

Next, let's try 23.

23 can be expressed as 6 + 8 + 9, or 5 + 7 + 9, etc.

Next, let's try 25.

25 can be expressed as 7 + 8 + 9, or 6 + 7 + 9, etc.

Finally, let's try 28.

28 cannot be expressed as the sum of three different one-digit numbers.

Therefore, the smallest two-digit number that is not the sum of three different one-digit numbers is 28.

So, the answer is E. 28.

To solve this problem, we need to understand that the maximum sum we can get from three different one-digit numbers is 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 = 45.

Now, let's start from the smallest two-digit number, which is 10, and see if we can express it as the sum of three different one-digit numbers.

10 can be expressed as 1 + 2 + 7, 1 + 3 + 6, 1 + 4 + 5, 2 + 3 + 5, and so on. So, 10 is not the answer.

Next, we check 11, 12, 13, 14, and so on. We find that all these numbers can also be expressed as the sum of three different one-digit numbers.

When we reach 15, we find that it cannot be expressed as the sum of three different one-digit numbers. The closest we can get is 1 + 5 + 9 = 15, but 5 is repeated.

Therefore, the smallest two-digit number that is not the sum of three different one-digit numbers is 15. So, the answer is B. 15.

To solve this problem, we need to understand that the maximum sum we can get from three different one-digit numbers is 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 = 45.

Now, let's start from the smallest two-digit number, which is 10, and see if we can express it as the sum of three different one-digit numbers.

10 can be expressed as 1 + 2 + 7, or 1 + 3 + 6, or 1 + 4 + 5, etc.

Next, let's try 15.

15 can be expressed as 1 + 5 + 9, or 2 + 4 + 9, or 2 + 5 + 8, etc.

Next, let's try 23.

23 can be expressed as 9 + 8 + 6, or 9 + 7 + 7, but the latter is not valid because 7 is repeated.

Finally, let's try 25.

25 cannot be expressed as the sum of three different one-digit numbers.

Therefore, the smallest two-digit number that is not the sum of three different one-digit numbers is 25.

So, the answer is D. 25.