Subscribe now

BrainTwister #7: Home primes

Can you solve this week’s logic puzzle? Plus our quick quiz and the answer to last week’s problem

By New Scientist

14 February 2024

New Scientist. Science news and long reads from expert journalists, covering developments in science, technology, health and the environment on the website and the magazine.

3D illustration, brain shaped maze. Concept image of study and brain behavior.; Shutterstock ID 2177110871; purchase_order: -; job: -; client: -; other: –

Shutterstock/ktsdesign

#7 Home primes

Set by Peter Rowlett

To find the home prime of a number, follow this procedure: first, find its prime factors; then concatenate these by writing the prime factors in size order to form a new number using all of their digits; then repeat until the resulting number is prime.

For example, 9 = 3 × 3, so its prime factors are 3 and 3. These concatenate to give 33. Now, find the prime…

Sign up to our weekly newsletter

Receive a weekly dose of discovery in your inbox! We'll also keep you up to date with New Scientist events and special offers.

Sign up

To continue reading, subscribe today with our introductory offers

View introductory offers

No commitment, cancel anytime*

Offer ends 2nd of July 2024.

*Cancel anytime within 14 days of payment to receive a refund on unserved issues.

Inclusive of applicable taxes (VAT)

or

Existing subscribers

Sign in to your account