This should work, or at least give you an idea:
MACRO: Add Numbers in a Variable [Example]
#### DOWNLOAD:
<a class="attachment" href="/uploads/default/original/2X/0/04d272ae14b8b08d4ae903fa89e21c93afd3e9ed.kmmacros">Add Numbers in a Variable [Example].kmmacros</a> (3.4 KB)
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### ReleaseNotes
1. The numbers can contain decimal point
2. Any character other than a digit or decimal point is treated as a boundary
3. All other characters are ignored
EDIT: 2016-10-01 12:51 CT
The regex works fine, but technically you don't need the vertical bar.
YOu can replace it with this:
`[\d\.]+`
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<img src="/uploads/default/original/2X/e/ed3c5e3feebede199e4a5ced26904ee396e0d2ae.png" width="680" height="947">