Novalucol back titration lab calculations

I had a lab today where we had the goal of figuring out how many moles of HCl were neutralized by one tablet of Novalucol. Novalucol is an antacid tablet containing magnesium hydroxide and calcium carbonate, 180.4 mg and 55 mg respectively. We had 0.984 grams of the tablet, we took one sixth of that meaning 0.164 grams and dissolved it in 100 ml 0.1 M HCl. We then divided these into four 20 ml beakers and titrated them with NaOH, our average value being 16.1 ml NaOH needed. My issue is these calculations and figuring out how I adjust for us having taken 1/6th of the tablet and 20 ml of the 100 ml solution to find the whole thing of how many mols 1 tablet could neutralize. I gave these calculations an attempt without adjusting for those factors if someone could let me know if I'm on the right track?
[![enter image description here](https://i.stack.imgur.com/UUFRv.jpg)](https://i.stack.imgur.com/UUFRv.jpg)


