A Strange Prime Number - 73,939,133

The prime number 73,939,133 has a very strange property.

If you keep removing a digit from the right hand end of the number, each of the remaining numbers is also prime.

It's the largest number known with this property.

Take a look: 73,939,133 and 73,939,13 and 73,939,1 and 73,939 and 7,393 and 739 and 73 and 7 are all prime!

MAGIC 1089 - A COOL MATH TRICK

• Write down a three-digit number whose digits are decreasing.
• Then reverse the digits to create a new number.
• Subtract the reversed number from the original number.
• With the resulting number, add it to the reverse of itself.

The number you will get is 1089!

EXAMPLE :

• Let us take 532 (three digit number in decreasing order).
• Then the reverse is 235.
• Subtract 532-235 to get 297.
• Now add 297 and its reverse 792,
• The resulting answer is 1089!

Division by addition

Multiplication TABLE 9 using FINGERS

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