How many squares, of any size, can be found on a standard chess board?

How many rectangles, of any size, can be found on a standard chess board?

Remember when counting the rectangles, that squares are also rectangles.

[Ref: ZLYW]

Hint: How many 8x8 squares are there, what about 7x7.

Answer: 1296 rectangles and 204 squares.

Puzzle 417

In this picture you can see 6 coins. Moving just ONE coin, can you form 2 lines, each with 4 coins?

[Ref: ZQLT]

Hint: Which one coin can you move? Try this puzzle with 6 coins of your own.

Answer: Simply move the right hand coin on top of the middle one.

Puzzle 418

You have the misfortune to own an unreliable clock. This one loses exactly 10 minutes every hour. It is now showing 5:00am and you know that is was correct at midnight, when you set it. The clock stopped 8 hours ago, what is the correct time now?

Hint: Determine how many clock minutes pass for each real hour.

Answer: 2:00pm.

The clock is losing 10 minutes every hour, so for every real hour that has passed, the clock will only show 50 minutes.

The clock now shows 5:00am, so we know that 300 clock minutes have passed. As every 50 clock minutes is actually a real hour: 300 ÷ 50 = 6 hours. So the clock stopped at 6:00am.

As the clock stopped 8 hours ago, the time now must be 2.00pm. QED.

Puzzle 419

Punctuate these words:

that that is is that that is not is not is not that it it is

[Ref: ZTOT]

Hint: Try saying it out loud.

Answer:
That that is, is: that that is not, is not. Is not that it? It is.

Puzzle 420

Using the BrainTracker grid below, how many words can you find? Each word must contain the central D and no letter can be used twice, however, the letters do not have to be connected. Proper nouns are not allowed, however, plurals are. Can you find the nine letter word?