Certain numbers have a magical quality. Use them in a mathematical problem and suddenly you are a mind reader, a magician, or even a genius.

Take good old 1089. It can turn you into an instant master mentalist. Here's how:First, write the figure 1089 on a piece of paper, fold it and hand it to somebody for safekeeping. What you put down is not to be read until you have completed your dazzling mental feat.

Next, ask your companion to write down any three figure number, emphasizing that the first and last digits must be different. Close your eyes, or turn you back while this is being done. Better still, have somebody blindfold you.

After your companion has written down the three figure number, ask him to reverse it, and subtract the smaller number from the larger. Example: 654 minus 456 equals 198.

Once this is done, tell your companion to reverse the new number. Example: 198 becomes 891.

Next, ask your companion to add the new number and its reverse together. Example: 198 and 891 equal 1089.

If all goes as planned, your companion will be absolutely flabbergasted. The number you wrote down at the start - 1089 - will be the same as the one calculated afterwards in the mathematical problem.

They say Albert Einstein used to take great delight in baffling friends with that puzzler. General Douglas MacArthur was another who had a favorite number game.

Visitors, especially young ones, often waited for the great man to perform a miracle, or at least utter something profound when they met him. The general could not always live up to his press notices.

So MacArthur adopted what he described as "the old number 115" as a method of maintaining his image, having some fun and leaving his guests mystified and dumbfounded.

Ask your companion to write down the number of the month in which he was born. (January is 1, February is 2 and so on).

Turn your back so you cannot see what your companion is jotting down in response to your instructions. Then have that person write down:

Month of birth (Example: February) 2

Double it (4)

Add 5 (9)

Multiply by 50 (450)

Add companion's age (example: 40) 490

Subtract 365 (125)

At this point, ask your companion to call out the total, which, in this case, is 125. Then in your head quickly and secretly add 115. You will end up with 240. In a loud voice proclaim: "Why you were born in February and you're 40!"

Here's how you did it. The first number - and the second if the total is a four digit number - will indicate the month, once you've added good old 115. The last two numbers will indicate the age.

This trick will work no matter what the age or month of birth, because you have good old 115 on your side. At least it always did for MacArthur.

Here's a trick involving the number 5. You may not be able to figure it out, but it always works.

Ask somebody to think of a number and keep it a secret. Then ask the person to double the secret number and then multiply by five. Finally ask the total.

Whatever the total is, knock off the last digit and you will have the secret number the person mentally picked at the start.

Then there's 3. Take a number. Double it. Add 9. Subtract 3. Divide by 2. Subtract your original number and your answer should be 3. Three works for you twice in that one.

The same basic trick can also work with 4. Take a number. Double it. Add 12. Subtract the remarkable 4. Divide by 2. Subtract your secret number.

You've got 4.

How about old 37? Three is a factor in this one.

Multiply 37 three and you have 111.

Jump up three numbers to 6, and multiply 37 again and you have 333.

This "jump-up-three" routine works all the way up to 27 (27 times 37 is 999). After that, old 37 loses its magic.

Finally, a number game called "The Best Year of Your Life."

1. Write down the year you were born.

2. Write down an important year during your lifetime.

3. Next, put down the number of years that have elapsed since that important year.

4. Put down your age this year on your birthday.

5. Add up the numbers on your list.

6. Divide by two.

If your mental computer is working - you should have your vintage year.

Use this knowledge wisely.