MATH TRICK - THE 11 RULE

 

The "11 Rule" is a quick math trick for multiplying two-digit numbers by 11. Here's how it works:

1. For a Number Like AB: To multiply a two-digit number by 11, where A and B are the digits, follow these steps:

   • Add A and B: This gives you a middle digit.
   • Place the result between A and B: Form a new number.

   For example:

   • To Multiply 34 by 11:
     1. Add the digits: $3 + 4 = 7$.
     2. Place this sum between the original digits: 374.

2. If the Sum is 10 or More:

   • Add the carry to the left digit and adjust accordingly.
   • For instance, $58 \times 11$:
     1. Add the digits: $5 + 8 = 13$.
     2. Place 3 in the middle and carry 1 over to the left: $58 + 58 = 638$.

This method makes multiplying by 11 fast and straightforward for two-digit numbers.