If 15th January, 2020 was a Wednesday, then what day of the week was it on 31st December of that year?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Thursday
The weekday repeats every 7 days, so only the odd days, the days left over after whole weeks, move it forward. 2020 is divisible by 4, so it is a leap year of 366 days, with 29 days in February.
Days left in January after the 15th: \(31-15=16\)
Days from 1st February to 31st December: \(366-31=335\)
Days from 15th January to 31st December: \(16+335=351\)
\(351=50\times7+1\), so there is 1 odd day
Wednesday + 1 day = Thursday
Tip: Check for a leap year first. Counting 2020 as 365 days gives 350 days, a whole 50 weeks, and the wrong answer Wednesday, Option (1).