I have question about byte_math

payload

/* 01 02 03 04 05 06 07 aa ff 0a 31 32 33 34 35 36 37 0a */

byte_math:bytes 1, offset 13, oper +, rvalue 0, result var, bitmask 0xf0;

var is 0x30 or 0x03 ??