Thursday, January 4, 2018

The 1729 Hangover :)

So I was really surprised when this familiar number showed up; unexpectedly, while I was computing for something else.....

Incidentally, I was with my students when this 'accident' happened...  And I could not contain my excitement, but had to call them to celebrate this...

I shouted -- "Hey guys... Did you all know that 1729 can be made using the first five natural numbers, and that too in the same order?? "

With this announcement, they simply left what they were doing and just dived into my calculator....No wonder they too were awestruck with this revelation :)

(though the machine just showed 54 x 32 = 1728, but they could infer that adding 1 one would yield that special number -- 1729)

For those, who are unaware about the story behind 1729 (the taxicab number or ramanujan-hardy number), plz check this video:

To this, one of the students immediately exclaimed - "Sir, it means this expression 54 x 32 should be equivalent to 12 cubed..."

And I was delighted with this remark of this 7th grade chap....   
(do you wonder, what would have made him think so?)

"Yes, shouldn't it be?", I countered him.

"Yes, it should be!", affirmed the other student with confidence.

And in next moment, he picked up the chalk to prove this statement on the board.... :)
And others too surrounded him to - as if to witness the climax !

I know at first, this incident might seem quite normal or 'what's so great about this?' types...

However, if one observes closely - esp school maths teachers like me - there are definitely some surprising and interesting moments for us, in this short incident...

Will be glad if you can find at least couple of those :)

Thanks and Regards
Rupesh Gesota

PS: Students belong to marathi medium government school (class-7 and 8) based at Navi-Mumbai. To know more about their Maths Enrichment program, check this link:


  1. (54x32)+1 = the famous number.
    Loved reading the discovery!

  2. Thanks a lot for posting this post, Your post has always been an informative source for me.
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