[LMB] Education for men

Joel Polowin jpolowin at hotmail.com
Wed Sep 8 22:07:52 BST 2021

Greg Hennessy <greg.hennessy at cox.net>
> I once posted, I don?t know if It was on this list or Facebook, the 
> steps needed to subtract large numbers using Roman Numerals. They are 
> almost the same as the steps used in the New New Math.

Consider the following subtraction problem: CCCXLII - CLXXIII.

You can't take III from II,
II is less than III,
So you look at the XL in the Xs place.
Now that's really XXXX,
So you make it XXX,
Regroup, and change X to VV,
Then change that to VIIIII,
And you add VIIIII to the II to get VIIIIIII
And you take away III, that's VIIII.
Which is VIV which is IX.
Is that clear?

Now instead of XL in the Xs place
You've got XXX,
'Cause you added X to the II,
But you can't take LXX from XXX
So you look in the Cs place.

>From the CCC you then use C
To make LL
(And you know why XXX plus minux X plus LL
Is LLXXX plus minux X?
'Cause addition is commutative, right.)
And so you've got LLXX
And you take away LXX
And that leaves LX...

Well, L, actually.
But the idea's the important thing.

Now go back to the Cs place,
You're left with CC,
And you take away C from CC,
And that leaves...?

Everybody get C?  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!

(With apologies to Tom Lehrer.)


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