Numeric expressions consist of combinations of numeric constants, numeric variables, ordinary numeric literals, binary operators, and parentheses. See:

Numeric expressions can contain register-relative or program-relative expressions if the overall expression evaluates to a value that does not include a register or the program counter.

Numeric expressions evaluate to 32-bit integers. You can interpret them as unsigned numbers in the range 0 to 2³² – 1, or signed numbers in the range –2³¹ to 2³¹ – 1. However, the assembler makes no distinction between –n and 2³² – n. Relational operators such as >= use the unsigned interpretation. This means that 0 > –1 is {FALSE}.

a   SETA    256*256           ; 256*256 is a numeric expression
    MOV     r1,#(a*22)        ; (a*22) is a numeric expression