& only works on numbers that fit in an IV (a signed integer type) or UV (an unsigned integer type). This range is -2,147,483,648..4,294,967,295 for you. Without use integer;, 872_415_232 + 4_278_190_080 produces a number larger than that, so & produces junk. Specifically, it returns the largest UV (4,294,967,295 for you), which %d casts to an IV (-1).

In reply to Re: perl arithmetic is killing me! HELP! by ikegami
in thread perl arithmetic is killing me! HELP! by harangzsolt33

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