Symfwnw ki egw, h (ma8hmatikh) analysh akolou8ei

8etw:
Ps: Pragmatiko Shmera
Ys: Ypo8etiko Shmera
Yx: Ypo8etiko X8es
psaxnw to Ps.
a. 3ekinontas anapoda:
"tote me8aurio 8a htan Kyriakh"
Ys+2=Kyriakh ==> Ys=Paraskeyh (1)
b. gnorizontas oti:
"ean to aurio htan ex8es"
Ps+1=Yx (2)
c. kai 3erontas oti:
"Ypo8etiko Shmera plhn meion mia mera = Ypo8etiko Ex8es"
Ys-1=Yx (3)
exoume:
(2),(3) ==> Ys-1=Ps+1 (4)
(1),(4) ==> Paraskeyh-1=Ps+1==> Paraskeyh-2=Ps ==> Ps= Tetarth
Pragmatiko Shmera = Tetarth 