Arithmetic operations in bash,ksh,sh

Shell Programming and Scripting
1

Guys,

The below expression is valid in which shells (sh,ksh,bash,csh)?

VAR1=2
VAR2=$(($VAR1 -2))

Thanks

2

In modern unix it is valid in all of them. "sh" is the Posix shell.
In older unix where "sh" is the old Bourne Shell it is not valid.