2 molecules of TP (2 x 3C) join to make 1 hexose sugar (6C), which can be used to make larger carbohydrates.
The Calvin cycle needs 6 turns to produce 2 TP molecules:
6 turns of the cycle need 18 ATP and 12 reduced NADP from the LDR.
This keeps the cycle going and makes sure there’s always enough RuBP ready to combine with CO2 taken in from the atmosphere.