# Multiply by 5 In Your Head

Multiplying by 5 mentally is easy since you just divide the number to be multiplied by 2 and multiply the result by 10, (also very simple, by just adding 1 zero to the number or if the number has a .5, just move one decimal place to the right).

### Examples:

34 × 5

Thought Process:

1. 34 ÷ 2 = 17

2. 17 × 10 = 170

Therefore, 34 × 5 = 170

63 × 5

Thought Process:

1. 63 ÷ 2 = 31.5

2. 31.5 × 10 = 315

Therefore, 63 × 5 = 315

There are many posts about more sophisticated mental multiplication techniques coming up, though I have to cover the basics first for the sake of completeness.

### Posted by Edmark M. Law

My name Edmark M. Law. I work as a freelance writer, mainly writing about science and mathematics. I am an ardent hobbyist. I like to read, solve puzzles, play chess, make origami and play basketball. In addition, I dabble in magic, particularly card magic and other sleight-of-hand type magic. I live in Hong Kong. You can find me on Twitter` and Facebook. My email is edmarklaw@learnfunfacts.com

## 25 thoughts on “Multiply by 5 In Your Head”

1. Wow you are incredible! Thank you for following me… am so happy to follow you back😀

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2. Oh! I loved this one. I just didn’t knew this one. Thank you, for sharing such a magical way to multiply anything by 5.

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1. Interesting. Where did you learn it?

I asked since I haven’t found a reference of this yet. I have no doubt that this method has been around for a while now but the only reason I know this is I found the theorem myself.

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2. I didn’t knew the theorem. Just the trick, that’s it. But that’s quite interesting to know, that you yourself have made the

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3. . Are we soon gonna to have the next Euclid in the form of Edward Law. Sounds very perfect. All the best for the future .

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4. It should be Edmark Law :D

Nah, Euclid is too great. There are even people who suspect that “Euclid” was actually a group of people akin to the group Nicolas Bourbaki during the 20th century.

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1. From what I’ve seen from your posts, your grammar is good.

While I’ll never accept even minor grammatical errors on academic papers, it’s not that big of a deal in other types of writings as long as you don’t commit basic errors, and your writings are not ambiguous.

Besides, the English language is a continuously evolving language and it is mostly defined by usage instead of a fixed set of stringent and encompassing rules.

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3. Where were you when I needed you in my school years??? Lol. This is awesome. Never to late to learn!

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4. Brilliant, Edmark. This method is great for my 10-year old daughter. ᕕ( ᐛ )ᕗ

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5. wandaintn says:

My husband does it this way, but I get confused when I try it. I’ll stick with the way I was taught in grade school, my brain doesn’t handle change very well! ;)

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1. It doesn’t really matter. We should use the methods that are the easiest for us. That’s why in mathematics, there are so many ways to solve a problem, especially in higher mathi.

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