Let's dork it up and do the fare hike math

MTA Subway fare hike details out:
On Feb 27:

• 7-Day Metrocards go up from $21 to $24
  
• 30-Day Metrocards go up from $70 to $74

Prepare to be dazzled by the awesome math. [click here to continue]This means the number of rides you have to make the cards worthwhile go up from 11 to 12 for 7 days, and from 35 to 37 for 30 days.

This means that if you work 5 days a week and make 10 weekday trips, you have to make at least one weekend round trip to make the weekly card worthwhile. For 10-11 rides, the $20 card is a better deal.

The monthly card is the same as the cost of 19 round trips. But there are 22 weekdays during a 30-day period, so barring holidays, if you just ride the subway to and from work, each ride costs $1.68 (up from $1.59).

Now, the grace period. You can use the pre-hike card through the following dates:

• 7-day: March 7
  
• 30-day: April 3

The last day you can buy the $70 Metrocard is Feb 26. That gives you 36 days to use the card after it goes off the market and you can get a pro-rated refund after April 3.

If you ride the subway everyday, you can save the most money if you buy one or two 30-day cards before Feb 27. If your current Metrocard expires before March 4, you can start your next 30-day card, start another one before April 3 and take the refund. If your current one expires after March 4, you can use the next one through April 3 and get a refund.

For example, my current 30-day expires on March 10. I can buy a $70 card before Feb 27, then start using it on March 11. It's supposed to be good through April 9, but it goes dead after April 3. I should get 6 days out of the 30 back, so my $70 card should end up costing $56 after refund. Should.

God, that was way too much math to save... how much?