Faster than a Calculator

Faster than a Calculator

Technology and apps have made daily calculations something we don’t need to think about anymore. So it’s impressive when you can speedily outthink your trusty calculator. Grab a friend and try it out.

Guide lines
Ready, Steady, Go!


I’m going to challenge a calculator’s speed and have the answer before the calculator does. Think it’s possible?

Lend me your ears

Ask the person to write down any three-digit number they like.


You sure you want that number, you can change it if you like?

Once they’ve settled on a three-digit number, have them write it down. Then hand them the calculator to start the number challenge.

Seal the Deal and Reveal

Ask them to multiply the number by 7, then by 11 and finally by 13.

Before they can push equals for the answer, call out the same three digits they picked and repeat the exact same three digits to create six digits in total.

Example: 414 becomes 414 414.

And 987 becomes 987 987.

You’ll know the answer as soon as they give you their chosen three digits, every time.

Some extra lines you can try

  • It’s like being a human computer, it’s a gift.
  • The numbers don’t lie, and neither do I.
  • According to my calculations, I’m quicker than a calculator.
Alternative ending

Try going the other way. By dividing the six-digit number by 13, 11 and then 7. It gets you back to the original three digits.

Anticipated responses and retorts

Are you a numbers wizard?

When it comes to 7, 11 and 13, then yes.

Do they numbers ever lie?

Only if they are spoken by a politician.

Is life all about numbers?

Life is all about breaking the ice – numbers help us to do that.
Good follow ups
When & where
When to use it
  • When you want to talk about the numbers.
  • When you want to get people very curious.
  • When you want to have some fun with maths.
Where to use it
  • customer visits
  • team building events
  • mentoring
  • socializing
Getting ready
Items required
  • A mobile phone with a calculator, and a pen and paper
  • Just remember the numbers 7, 11 and 13.
Training required
  • Try this once by yourself and you will be good to go.
Watch out (potential unexpected effects)
  • You could be recruited by an accounting firm.

type type

Do It Yourself (DIY)

material material

a pen and paper and a mobile phone calculator app

size size

pens and paper are everywhere and we all have phones in our pockets

durability durability

this one is industrial strength

source source

the ether

time to impact time to impact

pretty much there and then

size of audience size of audience

one-on-one works best

possible health risk possible health risk

numbers, numbers, numbers

reusable how many times you can use it

once or twice

training needed training needed

try this once on your own and you will be a numbers whiz

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