FOOL = ULLO
Solution 26 letters divided into 2 parts A - M = 1 - 13 N - Z = backward counting 13 - 1
F=6th letter so in backward 6th letter is U I=9th Letter Backward 9th is R N=13 in Backward M is 13th D = 4th letter W is 4th from Back
ULLO (atbash cipher)
If 397 is coded as 210191, 459 is coded as 360881 and 123 is coded as 030260
Then what is the code for 789?