-1 OR 5*5=25

It depends on the language/interpretation. Here are the common ones:

• General boolean logic (nonzero is true): -1 is true, and 5*5=25 is true, so True OR True → True (i.e., 1).
• Python-style expression (-1 or 5*5==25): evaluates to -1, because -1 is truthy and the 'or' operator short-circuits, returning the first truthy value.
• Bitwise OR on integers (-1 | 25): in two's complement, -1 has all bits set, so the result is -1.

If you tell me the language or what form you want (true/false vs a numeric value), I can tailor the answer.