p. 20, problem 13: should be "2" (not "1") if |i-j|=1 (thank you Anthony A.)
p. 23, problem 22: should be "diameter" instead of "radius"; clarification: the new coin must be of the same size as the previous ones (discovered by the author)
p. 44, problem 6: should be "Chapter 1." (discovered by the author)
p. 81, problem 6: should be "square" instead of "rectangle." Of course, a square is a special case of a rectangle, but "6 by 6 square" sounds better (discovered by Laura M.)
p. 86, problem 5(d): should be "implication" instead of "biconditional" (thanks Anthony A.)
p. 89, problem 5(d): square brackets rather than parentheses should be used for matrices, for consistency (discovered by the author)
p. 109, problem 15: need to indicate that this solution is to part (a) (discovered by the author)
p. 133: need solution to problem 5 (discovered by the author)