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== Problem ==
Leap Day, February 29, 2004, occured on a Sunday. On what day of the week will Leap Day, February 29, 2020, occur? 

<math> \mathrm{(A) \ } \textrm{Tuesday} \qquad \mathrm{(B) \ } \textrm{Wednesday} \qquad \mathrm{(C) \ } \textrm{Thursday} \qquad \mathrm{(D) \ } \textrm{Friday} \qquad \mathrm{(E) \ } \textrm{Saturday} </math>

== Solution ==
There are <math>365</math> days in a year, plus <math>1</math> extra day if there is a Leap Day, which occurs on years that are multiples of 4 (with a few exceptions that don't affect this problem). 

Therefore, the number of days between Leap Day 2004 and Leap Day 2020 is: 

<math> 16 \cdot 365 + 4 \cdot 1 = 5844 </math>

Since the days of the week repeat every <math>7</math> days and <math> 5844 \equiv -1 \bmod{7}</math>, the day of the week Leap Day 2020 occurs is the day of the week the day before Leap Day 2004 occurs, which is <math>\textrm{Saturday} \Rightarrow E </math>. 

== See Also ==
*[[2006 AMC 10B Problems]]

*[[2006 AMC 10B Problems/Problem 15|Previous Problem]]

*[[2006 AMC 10B Problems/Problem 17|Next Problem]]

[[Category:Introductory Number Theory Problems]]