Thirty is an even number.
Дарахти чормағз баъди сӣ сол меваи хуб медиҳад.
A walnut tree gives good fruit (produce) after thirty years.
In Tajik, the noun following a number does not take the plural ending (ҳо, он).
When a suffix is attached to a word ending in ӣ it is changed to и. Example –
яксаду сию панҷ: one hundred and thirty five