Question: do synchro summons have to be exact?
Answer: 1) Rulebook, page 14: "They can be Synchro Summoned from the Extra Deck by sending 1 face-up “Tuner” monster and any number of face-up non-Tuner monsters from your side of the field to the Graveyard, when the sum of all their Levels is exactly equal to the Level of the Synchro Monster."