This is what I did today: continuity correction

Normal Approximation, Continuity Correction

http://www.stat.yale.edu/Courses/1997-98/101/binom.htm

$\\\ P[X = 100]\ becomes\ P[99.5\leq X\leq100.5] \\\ P[X\leq100]\ becomes\ P[X\leq100.5] \\\ P[X%3C100]\ becomes\ P[X\leq99.5]$