A riddle problem is a question or statement intentionally phrased so as to require ingenuity in ascertaining its answer or meaning, typically presented as a game. Below are a list of the past problem of the week riddles in descending chronological order.

A man told his son that he would give him $1000 if he could accomplish the following task. The father gave his son ten envelopes and a thousand dollars, all in one dollar bills. He told his son, "Place the money in the envelopes in such a manner that no matter what number of dollars I ask for, you can give me one or more of the envelopes, containing the exact amount I asked for without having to open any of the envelopes. If you can do this, you will keep the $1000." When the father asked for a sum of money, the son was able to give him envelopes containing the exact amount of money asked for. How did the son distribute the money among the ten envelopes?

Answer:

The contents or the ten envelopes (in dollar bills) should be as follows: $1, 2, 4, 8, 16, 32, 64, 128, 256, 489. The first nine numbers are in geometrical progression, and their sum, deducted from 1,000, gives the contents of the tenth envelope.

Two travellers spend from 12 o'clock to 6 o'clock walking along a level road, up a hill and back again. Their pace is 4 mph on the level, 3 mph uphill, and 6 mph downhill.

How far do they walk and at what time do they reach the top of the hill?

An officer wishing to arrange his men in a solid square found by his first arrangement that he had 39 men left over. He then started increasing the number of men on a side by one, but found that 50 additional men would be needed to complete a new square.

How many men did the officer have?

Answer:

The officer had 1975 men. When he formed a square measuring 44 by 44, he had 39 men over. When he tried to form a square 45 x 45, he was 50 men short.

Ben walked into a hardware store and asked the price of some items. The salesman said: One costs $1, Eight costs $1, Seventeen cost $2, One hundred four costs $3 and One thousand seventy two costs $4. What was Ben buying?

Answer:

Ben was buying home address numbers and they cost $1 per digit.

Lily is a lillypad in a small pond. Lilly doubles her size each day, On the 20th day she cover the whole pond. On what day was Lily half the size of the pond?

Answer:

Day 19, it's not 10 because on day 20 she doubled from day 19, so 19 must be half the size of the pond.

Find four numbers, the sum of which is 45, so that if 2 is added to the first number, 2 is subtracted from the second number, the third number is multiplied by 2 and the fourth number is divided by 2, then the four numbers so produced are all the same. What are the four numbers?