I have 33,000 pairs of values from a logger.
- Time, concentration
How do I plot (or extract) every 20th value (or some other defined interval)?
Any ideas please (macro, VBA NOY manual selection).

I have tried past link row1, row10, row20 and dragging to extend the range
but this gives me row1, row20 row30 row2 row21 row31 etc

I want to end up with
row 1 data
row10 data
row 20 data

etc

Thanks. mel