Several hundred years ago mathematicians realised that there were a lot of problems they could solve if they had a way to talk about numbers less than zero. So they decided to write 0-1=-1, which is read as “negative one” and means one less than zero. It’s easy to say what 12-11 is, so shouldn’t 11-12 have an answer too?
The first set of rules for dealing with negative numbers was stated in the 7th century by the Indian mathematician Brahmagupta, (598 – 670). He used the ideas of ‘fortunes’ and ‘debts’ for positive and negative.
The author is an educational consultant with Sparsh, a division of SEED infotech at Pune. She can be reached at firstname.lastname@example.org .