Forum:Mathmech Equip + Damage Calculation rulings

Hello, i have a ruling question concerning primarily the equip spell Mathmech Billionblade Nayuta, and secondarily cards like Mathmech Division. For the example, let's say Player A has a 5000 ATK monster, say FGD. Player B has Geomathmech Final Sigma equipped with Billionblade. FGD declares an attack on the synchro cyberse. During damage calculation, the equip effect is activated, and sends Division from the deck to the graveyard. Two questions:

1 - Minor: Division was sent to the GY as a cost; If player B chooses to activate its ATK halving effect on FGD, does said effect activate in a SEPARATE chain after the spell increases the ATK of the synchro by 1000 atk?

2 - Major: This question applies assume the answer to 1 is "Yes" (aka Division effect resolves in a separate chain); which happens / resolves first? Does the 5000 ATK FGD destroy Final Sigma by battle, THEN Division's effect activates and makes it 2500 atk? Or during the same damage calculation, does Division weaken FGD BEFORE the battle happens, so Final Sigma manages to destroy FGD by battle?

Any details as to why X happens are welcome.

Thank you in advance for reading, and answering. Imadmagician (talk • contribs) 17:14, 22 December 2019 (UTC)