What was the day of the week on 28th May, 2006?

Goal

• Find the weekday on 28 May 2006.

Anchor

Jan 1, 2006 was a Sunday.

Step 1: Day-of-year for May 28 (non-leap year)
Jan 31 + Feb 28 + Mar 31 + Apr 30 + May 28 = 31+28+31+30+28 = 148Offset from Jan 1 = 148 − 1 = 147

Step 2: Take modulo 7
147 mod 7 = 0 ⇒ same weekday as Jan 1Therefore 28 May 2006 = Sunday

Final Answer
Sunday.