Rule
When you multiply a number with a 10, you just put one zero next to that number. When you multiply a number with a 100 you put two zeros next to that number. And when you do similar with a 1000 you put three zeroes and so on and so forth.
Example
7 X 10 = 70 7 X 100 = 700 7 X 1000 = 7000
You try with 10s
25 X 10 = 67 X 10 = 245 X 10 = 200 X 10 =
You try with 100s
25 X 100 = 67 X 100 = 245 X 100 = 200 X 100 =
You try with these
25 X 1000 = 67 X 10 = 245 X 100 = 200 X 100000 =