## THE FOUR SEVENS.

(

Money Puzzles)

In the illustration Professor Rackbrane is seen demonstrating one of the

little posers with which he is accustomed to entertain his class. He

believes that by taking his pupils off the beaten tracks he is the

better able to secure their attention, and to induce original and

ingenious methods of thought. He has, it will be seen, just shown how

four 5's may be written with simple arithmetical signs so as to

represent 100. Every juvenile reader will see at a glance that his

example is quite correct. Now, what he wants you to do is this: Arrange

four 7's (neither more nor less) with arithmetical signs so that they

shall represent 100. If he had said we were to use four 9's we might at

once have written 99+9/9, but the four 7's call for rather more

ingenuity. Can you discover the little trick?

## Answer:

The way to write four sevens with simple arithmetical signs so that they

represent 100 is as follows:--

7 7

-- x -- = 100.

.7 .7

Of course the fraction, 7 over decimal 7, equals 7 divided by 7/10,

which is the same as 70 divided by 7, or 10. Then 10 multiplied by 10 is

100, and there you are! It will be seen that this solution applies

equally to any number whatever that you may substitute for 7.