Number nine will put you on the spot
Number nine will tie you up, oh, in a knot
When you're trying
Multiplying by nine
You might give it everything you've got
And still be stopped
If you don't know some secret way you can check on
You'll break your neck on Naughty number nine
Now the first thing to keep in mind
When you're multiplying by nine
Is that it's one less than ten
You see, nine is the same as ten minus one
So you could multiply your number by ten
And then subtract the number from the result
And you'd get the same product
As if you'd multiplied by nine
I mean, eight times nine is 80 minus eight
And seven times nine is 70 minus seven
And six times nine is 60 minus six
You could use those tricks
Because you must have some secret way you can beat it
Or else you'll meet it
With naughty number nine
Of course, it doesn't hurt
To know the table of nines by memory
One times nine is nine, and two times nine is 18
(Mean ol' number nine)
Three times nine is 27, and four times nine is 36
Five times nine is 45, and six times nine is 54
And seven times nine is 63
Eight times nine is 72, and nine times nine is 81
And ten times nine is 90
Now the digit sum is always equal to nine
I mean, if you add two and seven, the digits
You get nine, the digit sum
That's true of any product of nine
If they don't add up, you've made a mistake
Because you must have some secret way you can check it
Or else you'll wreck it
With naughty, nasty, mean old number nine