I saw a post on reddit asking whether imaginary numbers were actually any use at all.
My response was getting so long, I decided to post it here:
Here’s a bit of history about the words we use for numbers big enough to describe world populations and budgets.
Last week, I got to help my son learn subtraction with borrowing. He’s already learned how to subtract two-digit numbers when borrowing is not needed, as you can see from the picture below.
I was reading a book about numbers recently, and almost put it down when it started talking about prime numbers. The author had tried to work out the prime factors of 72, got as far as 2 x 2 x 2 x 9, then said “you guessed it, 9 is a prime number!” Arrgh!