Explain how the value of 7 in 327,902 will change if you move it to the tens place

In the initial number xx7,xxx; 7 is in the thousands place meaning its value is 7,000.
If it is moved to the tens place = xxx,x7x then it's value will decrease, it will become 70 only.

Every placement has its corresponding values, thus whereven the number 7 is place it is multiplied by its corresponding values (ones, tens, hundreds, etc).