Arithmetic Trick: Multiplying by 15
Hi all steemian friends, on this occasion, I would like to share another interesting basic trick of arithmetic, especially for students who want to master arithmetic. This trick is named as Multiplying by 15.
Today is the last day of school after you have studied for a year. To welcome it, your class will have a garden party. Your class has ordered 15 loaves of bread. Each bread is cut into 8 slices. How many slices of bread are there? To find out the answer, we will do an 8 x 15 count.
Here's the ways!
To multiply a two-digit number by the number 15, multiply that two-digit number by 10 (see Multiplication trick by 10). Determine how many numbers indicate half of the multiplication result. Then, sum the result with the original number. Let's try this trick to find out the answer to the above question.
Let's try with another example!
Always remember! In addition to multiplying by 10, then adding by half, we can add the original number by half. Then, multiply it by the number 10. In the example of the bread party, we add the number 8 by half (4) and get 12. Next, multiply that number by the number 10. We will get the answer, which is 120. You are free to choose which trick easier.
Let's practice again!
This is all about my explanation for this basic arithmetic trick, follow my post to get other arithmetic tricks, that I will explain in my next post. Hopefully, this article useful for me personally and for you all.
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STOPits a good trick ...What about multiplying with some other number rather than 15 only?
Thanks buddy for visiting my post and for your nice comment.
You can see my previous posts, I have shared many of tricks. Simple tricks for the beginning, step by step.
I like it and it's something that I do often in my head for such big numbers. I had not thought of writing it down though. I did write down some shortcuts on multiplying with 5's. You can see all 3 sections on my site.
https://steemit.com/education/@johnwjr7/fun-with-5-s-1
https://steemit.com/education/@johnwjr7/fun-with-5-s-2
https://steemit.com/education/@johnwjr7/fun-with-5-s-3
Please let me know what you think of those.
Nice! I like your posts. You look like very comfortable with the arithmetic. Thanks for sharing @johnwjr