thirtieth day of the month;  thirty days
 thirty-first day of the month;  thirty-one days
 Thirty Years' War (1618-1648)
 turning thirty and therefore becoming independent;  at thirty, one stands on one's own
 32nd anniversary of death
 thirty-three temples sacred to Kannon (Avalokitesvara)
 32nd note;  demisemiquaver
 the thirty guardian deities (a different one for each day)
 cesium 137 (Cs-137);  caesium 137
 36 Initials (system for transcribing initial consonants of Middle Chinese)