Subscribe now

Puzzle #102: Can you figure out a number with amazing properties?

24 February 2021

#102 Passport to success

My nine-digit passport number has some remarkable properties. Not only does it use all the digits from 1 to 9, but if I label the number ABCDEFGHI, then:

A is divisible by 1

AB is divisible by 2

ABC is divisible by 3

ABCD is divisible by 4

ABCDE is divisible by 5

ABCDEF is divisible by 6

ABCDEFG is divisible by 7

ABCDEFGH is divisible by 8

ABCDEFGHI is divisible by 9

You could program a computer to find this passport number, but there are shortcuts to figuring it out with a pen and paper.…

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

Popular articles

Trending New Scientist articles

Piano Exit Overlay Banner Mobile Piano Exit Overlay Banner Desktop