If you move one place to the left, the number will be ten times smaller, that is, multiplied by 0. 1 (don't ask me why, it's a decimal)

Let the original number be x, then the following number is 0.1x.

Get the equation

x-0. 1x= 1 1.7

0.9x= 1 1.7

x= 13

So the original number is 13.