This is Part II of Multiply by 11, Click Here to read Part I of this post. As you learnt in Part I how to multiply a two digit number with 11. Now, you will learn how to multiply 11 with more than two digits. As usual we deal with simple examples to explain the concept. Here is the first example how to multiply 11 with three digits number.
Example 1. Multiply 145 by 11
- Put a Zero(0) on left side so it become 0145
- Write down "units" place number, in other words, extreme right digit. On the right side, Here is, ___5
- For the "tens" place, add the 4 to the its "neighbor" (the 5). Write the answer : 9 below the 4.
- For the "hundreds" place, add the 1 to the its "neighbor" (the 4). Write the answer : 5 below the 1.
- For the "thousands" place, add the 1 to the its "neighbor" (the 0). Write the answer : 1 below the 0.
So, what is this technique or you might say that how does it works?
- Add a Zero(0) to extreme left.
- Write "units" place number digit as it is, on the extreme right side.
- Now for "ten", "hundreds", "thousands", "ten-thousands" places and so on. Start adding numbers from right to left.
- One more thing when you get "carry" don't forget to add into its "neighbor" on left side.
Note: This technique apply to all digits number to multiply with 11.
2-3 time practice and you will be able to multiply any digit number with 11.
Here are some problems for your practice, post the answers in your comments.
If you want to share your knowledge, comment, your experience or even a small problem. Feel free to express via comments. Soon, I'll back with new quick technique.