Field Calc to change one digit in a sequence Arcmap

Question

I have an 11 digit ID in one field I'll call "Current_ID". I would like to create a new field named "New_Field" and populate it with same value except I need to change the value of the 4th digit from a 5 to a 4.

Example: 
"Current_ID" = 1505000001
"New_Field" desired ID =  1504000001

Both field types are Double

400 records

How can this be done using Field Calc?

Answer 1

Use field calculator expression:

"Current_ID"-1000000

Answer 2

If you're always only changing the fourth digit to a 4 - In field calculator on the New_Field select Python parser, and input the following:

int('{}4{}'.format(str( !Current_ID! )[:3], str( !Current_ID! )[4:]))

This will replace the fourth digit with a 4 (whatever that fourth digit may be).

If it needs to be a number other than 4, change the number in {}4{}