I was inspired by this thread [url]http://theftalk.com/t11568-10-Easy-Arithmetic-Tricks.html[/url] to make this,, It fueled me to think if only 11 multiplied by a 2-digit number will have a pattern,, and I discovered some facts about multiplying by 11 and 111,, [quote][b]11 multiplied by a 2-digit number[/b] This trick is already explained in the thread I mentioned earlier,, Example: 11 x 23 Step 1: Copy the 2 and 3 as the first and last digit of the answer, respectively. [b]2_3[/b] Step 2: Add 2 and 3 for the middle digit of the answer. The middle digit is 5. [b]2_(2+3)_3[/b] Answer: 253[/quote] [quote][b]11 multiplied by a 3-digit number[/b] This trick is almost the same as multiplying 11 by a 2-digit number,, Example#1: 11 x 235 Step 1: Copy the 2 and 5 as the first and last digit of the answer, respectively. [b]2 _ _ 5[/b] Step 2: To find the the second digit of the answer, add 2 and 3. The second digit is 5. [b]2_(2+3)_ _ 5[/b] Step 3: To find the third digit, add 3 and 5. The third digit is 8. [b]2_(2+3)_(3+5)_5[/b] Answer: 2585 Example#2: 11 x 879 Step1: Copy 8 and 9 as the first and last digit of the answer, respectively. [b]8 _ _ 9[/b] Step2: Again, add 8 and 7 to find the second digit. The answer is 15. In this case it is more than 10 so we have to carry one and add it to the first digit which is 8. [b]8_(8+7)_ _ 9 so it would be like this (8+1)_5 _ 9[/b] Step3: Repeat step 2, this time add 7 and 9. The answer is 16. It is also more than 10 so we have to carry one to the second digit which is 5. [b]95_(9+7)_9 would look like this 9_(5+1)_69[/b] Answer: 9669[/quote] [quote][b]11 multiplied by a 4-digit number[/b] You can also use this trick in multiplying 11 by huge numbers,, Example: 11 x 2415 Step1: Copy 2 and 5 as the first and last digit respectively. [b]2 _ _ _ 5[/b] Step2: Add 2 and 4. [b]2_(2+4)_ _ _ 5[/b] Step3: Add 4 and 1. [b]26_(4+1)_ _ 5[/b] Step4: Add 1 and 5. [b]265_(1+5)_ 5[/b] Answer: 26565[/quote] [b]NOTE: The magic of 11 does not end here you can use that trick even with very big numbers.[/b] [quote][b]111 multiplied by a 3-digit number[/b] This is a very difficult trick to master but it really pays off to study this. Example#1: 111 x 324 Step1: Copy 3 and 4 as the first and last digit respectively. [b]3 _ _ _ 4[/b] Step2: For the second digit add 3 and 2. [b]3 _(3+2)_ _ _ 4[/b] Step3: For the middle digit, add 3, 2 and 4. [b]35 _(3+2+4)_ _ 4[/b] Step4: For the fourth digit add 2 and 4. [b]359 _(2+4)_ 4[/b] Answer: 35964[/quote] [b]P.S. Maybe some already know this but it is a pleasure for me to share this. This trick came from no source rather I thought of it by myself. See my post#30 on this thread to see I'm not lying about being good in Math [url]http://theftalk.com/t26356-p2-What-award-s-did-you-get%3F.html[/url],,[/b]