What is the product of$100\times 100$ ?

The correct option is (D).

We can calculate the product by using the steps given below. 

Step 1: Multiply 0 by each digit of 100

Step 2: Place a zero on ones place below the product obtained above.

Step 3:  Multiply 0 by each digit of 100

Step 4: Then again place a zero on ones place below the product obtained above.

Step 5: Now, multiply 1 by each digit of 100 

Step 6: Add the three products to obtain the final answer.

Therefore, the product of $100\times 100$ is $10000$.