In mathematics, every integer in a number has a place value. Therefore, the place value of a number is the value represented by a digit in a number based on its position in the number.
For example, consider the number 30.
3 is in the tens place while,
0 is in the ones place.
Going by the above explanation:
The digit in the ones place in each of the products (10,20,30,40,50,...90) is 0
For every product obtained, it will always have a ones place value of 0