Today is Sunday. After 87 days, what day of the week will it be?

Question: Today is Sunday. After 87 days, what day of the week will it be?

Solution:
Each day of the week is repeated after 7 days.

So, after (7 × 12) = 84 days, it will be Sunday.

After 85 days, it will be Monday.
After 86 days, it will be Tuesday.
∴ After 87 days, it will be Wednesday.