So there are only a few ways that numbers can start and end, so this shouldn’t be hard.
Let’s begin with how numbers end because it’s easier to think if any numbers at all start with something, so we can start from here and work backwards to make it easier on our heads.
E: numbers that end with one, three, five, nine or twelve. e.g. 8012 -> eight thousand and twelve
O: numbers that end with two. e.g. 100432 -> one hundred thousand, four hundred and thirty two
R: numbers that end with four. There aren’t any numbers that start with R, so we can forget this.
X: numbers that end with six. There aren’t any numbers that start with X, so we can forget this.
N: numbers that end with seven, ten, eleven, any of the teens (13, 14, 15, 16, 17, 18, 19), or one million itself, e.g. 9010 nine thousand and ten
T: numbers that end with eight, e.g. 20098 -> twenty thousand and ninety eight
Y: numbers that end with twenty, thirty, forty, fifty, sixty, seventy, eighty or ninety. There aren’t any numbers that start with Y, so we can forget this.
D: numbers that end with hundred or thousand. There aren’t any numbers that start with D, so we can forget this.
I think that’s all of them. So we can have Es, Os, Ns and Ts to deal with.
So let’s go over each of these in alphabetical order this time.
E: Starting with E is simple-ish. Those that begin with 8 fall into here.
I said before that numbers that end in 1, 3, 5 or 9 fall here. This isn’t the case for numbers that end in 11, 13, 15 or 19 so we have to look out for the tens digit. Numbers that end in 12 also fall in here.
N: Starting with N is simple-ish. Those that begin with 9 fall into here.
As for ending, because seven and seventeen fall into this, ANY number ending in 7 will fall into this category (yay!). Numbers ending in 10 fall here as well, as do 11, 13, 14, 15, 16, 17, 18 and 19. While 1,000,000 ends in N it begins with O so it isn’t part of this…
O: Those that begin with 1 fall into here (except 10, though that would end in N so it wouldn’t work anyway)
Numbers that end in 2, except ones that end in 12, nice and simple.
T: There’s a few ways to start with T. Those that begin with 2 and 3 fall here, as do those that start with 10, though that’s a bit complex…
Numbers that end in eight, except ones that end in eighteen, nice and simple.
I’m not sure how we should go through this.