After playing, I came up with:

@a=/.(?{$s+=$&})/g;
[download]

However, I have to have the @a=. If you run it without that, it only deals with the first number. *blinkblink* That's just so counter-intuitive.

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We are the carpenters and bricklayers of the Information Age.

Don't go borrowing trouble. For programmers, this means Worry only about what you need to implement.