1. Each week has 5 business days, and 20 = 4*5, so 20 business days 
   after Feb. 23 is exactly 4 weeks (or 28 calendar days) after 
   Feb. 23.  That's "Feb. 23+28", or "Feb. 51", or March 51-28, 
   or March 23.

2. The unit price for the 5-ounce bottle is $2 / 5 oz, or 0.4 $/oz 
   (40 cents per ounce).  The unit price of the 8-ounce bottle is 
   $3 / 8 oz, or 0.375 $/oz (37.5 cents per ounce).  The larger 
   bottle is a better deal.

3. circular reasoning or appeal to emotion (the former is a better
   answer, but since the word "alcoholic" has rather pejorative 
   connotations, there's an element of appeal-to-emotion here as well)

4. appeal to ignorance

5. (100 British pounds) ($1.67 / British pound) (1 pound of apples / $1.37)
   = (100)*(1.67)/(1.37) lbs of apples; that's about 122.

6. (100 Euros) ($1.169 US / Euro) ($1.336 CAN / $1 US)
   = $(100)*(1.169)*(1.336) CAN = $156 CAN.

7. (12 fluid ounces) (1.805 in^3 / fluid ounce)
   = (12*1.805) in^3 = 21.66, which is about 22. 

8. (100 w) (24 hours) (kw / 1000 w) ($0.10 / kw-hr)
   = $(100)*(24)*(0.10)/1000 = $0.24, or 24 cents.