How can patterns me divide multiples of 10

Dividing a number by 10 is probably the easiest thing to do, you just need to follow these rule :

1. If the number that has zero divided by 10, you just need to take out 1 zero
Example : 200 : 10  = 20

2. If the number that doesn't has zero divided by 10, you just need to put a comma in front of the last number
For example : 1998 : 1  = 199.8

hope this helps