Please note the following small mistakes/typos in the current text(fall 2017)

On page 8 of Chpt. 0 under exponents, there are typos in #1, text states 0^x = 1 (not true) and “0^0 is undefined” instead of saying indeterminate.

In chapter 0 exercises, #15 on page 12 in the answers, the natural number are said to be not closed under multiplication. (The natural numbers are closed under multiplication.)