Toilet paper math is the hardest kind of math. According to the print on various different packages of Charmin, and I could not make this up:

12 Mega Plus rolls = 54 Regular rolls

30 Double Plus rolls = 68 Regular rolls

12 Super Mega rolls = 72 Regular rolls

18 Mega rolls = 72 Regular rolls usually, but sometimes are sold as "Bonus Mega = 82 Regular rolls"