Sorting on last field

Shell Programming and Scripting
1

Hello
I am trying to sort on the last field and it seems to have lost ideas on what to do. the file am sorting looks like this

Tan\da\1223
hey\1234
two\three\think\4579

i want to sort on the last fields (1223, 1234 and 4579).
thank you

2 
> cat file7
Tan\da\1223
hey\1234
two\three\think\4579
stuff\this\20566
those\12

> cat file7 | awk '{FS="\\" ; $0=$0 ; print $NF"|"$0}' | sort -n | cut -d"|" -f2
those\12
Tan\da\1223
hey\1234
two\three\think\4579
stuff\this\20566
3

Thank you for your help, however when i tried
> cat file7 | awk '{FS="\\" ; $0=$0 ; print $NF"|"$0}' | sort -n | cut -d"|" -f2

It gave me the following error message:

awk: can't set $0
record number 1