When he added up the columns as above, he assumed that he must owe $1 to the bank. Was he right?
There is no reason whatever why the customer's original deposit of $100 should equal the total of the balances left after each withdrawal. The total of withdrawals in the left-hand column must always equal $100, but it is purely a coincidence that the total of the right-hand column is close to $100. For example:
There are three houses, and three utilities: gas, electricity and water. Your task is to connect each house to all three utilities. Therefore each house will have three lines and each utility will also have three lines. However, you cannot cross lines. You cannot pass lines through houses or utilities. You cannot share lines. Can you draw the 9 lines required?
Answer: This puzzle is a classic one which has no solution in 2D.
However, if you place the items on a doughnut shape in 3D you can solve it. In the picture below, E is linked to 3 by going over the top and re-entering through the hole in the middle.
There is a closed room with a light in it. Outside, there are 3 light switches.
You can flick any of the switches any number of times. You can only open the door and go into the room once. You know that the light is initially off and you can't see what happens when you flick the switches.
How can you determine which light switch operates the light?
Hint: What happens when you leave a light on for a while?
Leave switch 1 alone.
Flick switch 2 for 1 hour, then flick back.
Flick switch 3.
Now look. If the light is on, then the switch is 3, if the light bulb is warm, then switch 2, else switch 1.
Yesterday my mother asked me to buy some stamps. Stamps, in the land of BrainBashers, are available in 2p, 7p, 10p, 15p and 20p denominations. For three types of stamp I was asked to buy five of each. For the other two types of stamp, I was asked to buy six of each. Unfortunately I forgot which I was supposed to buy five of and which to buy six of. Luckily my mother had given me the exact money required to buy the stamps, £3.00 and the shopkeeper was able to give me the correct stamps. Which stamps did I buy?
Five lots of 2p, 7p and 15p and six lots of 10p and 20p. The shopkeeper rightly figured that I required five lots of each of the stamps, which came to £2.70, he also knew I required two more stamps which added up to the difference. QED.
Using the BrainTracker grid below, how many words can you find? Each word must contain the central G and no letter can be used twice. The letters do not have to be connected. Proper nouns are not allowed, however, plurals are. Can you find the nine letter word?