Tom Lehrer - New Math (11/2/2009) текст песни

Some of you who have small children may have perhaps been put in the embarrassing position of being unable to do your child's arithmetic homework because of the current revolution in mathematics teaching known as the New Math. So as a public service here tonight I thought I would offer a brief lesson in the New Math. Tonight we're going to cover subtraction. This is the first room I've worked for a while that didn't have a blackboard so we will have to make due with more primitive visual aids, as they say in the "ed biz." Consider the following subtraction problem, which I will put up here: 342 - 173.

Now remember how we used to do that. 3 from 2 is 9; carry the 1, and
if you're under 35 or went to a private school you say 7 from 3 is 6
but if you're over 35 and went to a public school you say 8 from 4 is
6; carry the one so we have 169, but in the new approach, as you know, the
important thing is to understand what you're doing rather than to get the right
answer. Here's how they do it now.

You can't take 3 from 2
2 is less than 3
So you look at the four in the tens place.
Now that's really four tens
So you make it 3 tens
Regroup, and you change a 10 to 10 ones
And you add them to the 2 and get 12
And you take away 3, that's 9.
Is that clear?

Now instead of 4 in the tens place
You've got 3
'Cause you added 1
That is to say, ten, to the 2
But you can't take 7 from 3
So you look in the hundreds place.

From the 3 you then use 1
To make ten ones.
(And you know why 4 plus minus 1
Plus 10 is 14 minus 1?
'Cause addition is commutative, right.)
And so you have 13 tens
And you take away 7
And that leaves 5...

Well, 6 actually.
But the idea is the important thing.

Now go back to the hundreds place
And you're left with 2.
And you take away 1 from 2
And that leaves...?

Everybody get 1?
Not bad for the first day!

Hooray for new math
New-hoo-hoo-math
It won't do you a bit of good to review math.
It's so simple
So very simple
That only a child can do it!

Now that actually is not the answer that I had in mind, because the book that I
got this problem out of wants you to do it in base 8. But don't panic. Base
eight is just like base ten really - if you're missing two fingers. Shall we
have a go at it? Hang on.

You can't take 3 from 2
2 is less than 3
So you look at the four in the eights place.
Now that's really four eights
So you make it three eights
Regroup, and you change an 8 to 8 ones
And you add them to the 2
and you get one-two base 8
Which is ten base 10
And you take away 3, that's 7.

Now instead of four in the eights place
You've got three
'Cause you added one
That is to say, eight, to the 2
But you can't take 7 from 3
So you look at the sixty-fours.

"Sixty-four? How did sixty-four get into it?" I hear you cry.
Well, sixty-four is eight squared, don't you see?
(Well, you ask a silly question, and you get a silly answer.)

From the three you then use 1
To make 8 ones
And you add those ones to the 3
And you get one-three base 8
Or, in other words
In base ten you have 11
And you take away 7
And 7 from 1 is 4.
Now go back to the sixty-four
And you're left with 2
And you take away 1 from 2
And that leaves...?

Now, let's not always see the same hands.
One, that's right!
Whoever got one can stay after the show and clean the erasers.

[§9 X2]

Come back tomorrow night. We're gonna do fractions.
Now I've often thought I'd like to write a mathematics text book someday because I have
a title that I know will sell a million copies. I'm gonna call it Tropic Of
Calculus.