To solve the problem, we need to multiply 6 by 3. Multiplication is a mathematical operation that combines two numbers to give a product.

The multiplication of 6 and 3 can be solved using the following steps:

1. Write down the numbers to be multiplied: 6 and 3.

2. Start with the first number, 6, and multiply it by the ones place digit of the second number, which is 3.
- Multiply 6 by 3: 6 x 3 = 18.

3. Write down the product, 18.

Therefore, the multiplication of 6 and 3 is equal to 18, which matches option 'D'.

Explanation:
- To multiply two numbers, we can use the multiplication table or the repeated addition method. In this case, we will use the multiplication table.
- The multiplication table for 6 shows that when we multiply 6 by 3, the product is 18.
- Multiplication is a way of adding a number to itself a certain number of times. In this case, we are adding 6 three times.
- Another way to visualize this is to think of 6 as a group of 3, and we have 3 groups of 6. So, when we multiply 6 by 3, we are essentially adding 6 three times, which gives us a total of 18.
- Therefore, the correct answer is option 'D', which states that 6 times 3 equals 18.

In summary:
- Multiplying 6 by 3 gives us a product of 18.
- This can be calculated using the multiplication table or by repeated addition.
- The correct answer is option 'D', which states that 6 times 3 is equal to 18.