ArtsAutosBooksBusinessEducationEntertainmentFamilyFashionFoodGamesGenderHealthHolidaysHomeHubPagesPersonal FinancePetsPoliticsReligionSportsTechnologyTravel

Speed Arithmetic - How to Multiply and Divide by 5 Without a Calculator

Updated on March 31, 2020
David3142 profile image

I am a former maths teacher and owner of DoingMaths. I love writing about maths, its applications, and fun mathematical facts.

Multiplying by the Number 5

How to Use Quick Mental Arithmetic to Multiply and Divide by 5

There are many instances in life when it's useful to be able to multiply or divide by 5, e.g. when splitting a bill between a group of 5, when calculating the price of 5 identical items etc. Of course, nowadays most of us can pull out our phone, bring up a calculator app and solve this, but if you know the correct method, it can often be substantially quicker to solve it mentally.

In this article I will show you how to multiply and divide by 5 quickly in your head, without the need for a calculator or even a piece of paper.

How to Multiply by 5

Let's look at solving 23 × 5. There are many ways to approach this using mental methods, but we're going to look at one particular method here which is super quick and easy to use on any example.

To start with, consider that 5 = 10 ÷ 2. By swapping the 5 in our original problem for this 10 ÷ 2, we get

23 × 5 = 23 × 10 ÷ 2

As multiplying by 10 and dividing by 2 are both much easier to do mentally than multiplying by 5, we can now split our sum up into these two easier steps. It doesn't matter which order you do them in, but I tend to divide by 2 first as it is generally slightly easier to halve the smaller number. So we get:

  • 23 ÷ 2 = 11.5
  • 11.5 × 10 = 115

So we get a final answer of 23 × 5 = 115.

Multiplying by 5: A Trickier Example

This method works with any example, so let's try a trickier example with a decimal number.

72.8 × 5

Again, we use our two steps of dividing by 2 and multiplying by 10:

  • 72.8 ÷ 2 = 36.4
  • 36.4 × 10 = 364

to give us a final answer of 72.8 × 5 = 364.

How to Divide by 5

In order to divide by 5 we use almost the same technique as before but reverse the operations. Let's try 145 ÷ 5.

As with multiplying, we are going to use the fact that 5 = 10 ÷ 2, but this time as we are dividing by 5, we will switch the operations around so get:

145 ÷ 5 = 145 ÷ (10 ÷ 2)

= 145 ÷ 10 × 2

Breaking this down into separate steps give us:

  • 145 ÷ 10 = 14.5
  • 14.5 × 2 =29

So 145 ÷ 5 = 29.

Dividing by 5 - Trickier Examples

As with the multiplying method, this method also works with trickier examples.

Let's try 2410 ÷ 5.

  • 2410 ÷ 10 = 241
  • 241 × 2 = 482

Or even with a decimal number, 365.6 ÷ 5.

  • 365.6 ÷ 10 = 36.56
  • 36.56 × 2 = 73.12

For Further Examples Watch This Video From the DoingMaths YouTube Channel

© 2020 David


This website uses cookies

As a user in the EEA, your approval is needed on a few things. To provide a better website experience, uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at:

Show Details
HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
LoginThis is necessary to sign in to the HubPages Service.
Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
AkismetThis is used to detect comment spam. (Privacy Policy)
HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the or domains, for performance and efficiency reasons. (Privacy Policy)
Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
MavenThis supports the Maven widget and search functionality. (Privacy Policy)
Google AdSenseThis is an ad network. (Privacy Policy)
Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
Index ExchangeThis is an ad network. (Privacy Policy)
SovrnThis is an ad network. (Privacy Policy)
Facebook AdsThis is an ad network. (Privacy Policy)
Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
AppNexusThis is an ad network. (Privacy Policy)
OpenxThis is an ad network. (Privacy Policy)
Rubicon ProjectThis is an ad network. (Privacy Policy)
TripleLiftThis is an ad network. (Privacy Policy)
Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)
ClickscoThis is a data management platform studying reader behavior (Privacy Policy)