Tuesday, June 06, 2006

Finger Arithmetic Part Two

Continuing finger arithmetic from Part One. This third part is called Part Two. We start addition. It may seem as if the lesson moves slowly. Take your time. The harder stuff builds on this easy stuff.

First, we'll add one and one. Start with a fist on your right hand. Put out a finger to represent one. Add another finger. Read the answer out loud: two.

You might think we've already covered this. And you'd be right. We have added one repeatedly in order to count. In some sense, this is nothing new.

Next example. Add one plus two. Start with a fist on your right hand. Put out a finger to set one. Add two fingers to it. Read the answer out loud: three.

Next example. Add two plus two. Start with a fist on your right had. Put two fingers out to set two. Add two fingers to it. Read the answer out loud: four.

The whole set of possible examples here are: 0 + 1, 0 + 2, 0 + 3, 0 + 4, 1 + 1, 1 + 2, 1 + 3, 2 + 2, 3 + 1. Practice these all week.

Extra credit. Add ten plus twenty. Start with a fist on your left hand. Put out a finger to set ten. Add two fingers to it. Read the answer out loud: thirty.

That's small number addition. Remember to practice the drills every day. Don't forget to bring your fingers with you, everywhere. Do you have five minutes? What are you waiting for?


yep, it's me.... said...

what a delicious headache i have now!
I'm going back to the 666 site - and in 666AD they didn't yet know about 666 -cuz- the bible hadn't been translated and anyway in those days 666 was just the symbol over the door like banks in the UK for the non-literate..
oh headache doubled.....

Stephen said...

Though this was posted on the day of the beast, finger math won't get to three digits until after subtraction. That may be around part twenty.

Now then, i mentioned binary arithmetic, allowing one to count to over 1,000. In binary, 666 is 1010011010. Think of it as 10100 11010 with the little pinky and middle finger of the left hand up, and the thumb, index finger and ring finger of the right hand up. That's 666. I find the right hand is a little awkward.

Anonymous said...

One could use this, whether binary or base-ten, to translate ghetto/gang/hiphop hand signs. That would likely make at least as much sense as anything anyone else says they mean.

Sister Mary Hasta said...

Dude, dude, DUDE!

YOU are the kind of parent I, as an elementary teacher (in my alternate life) LOVE!

I had a parent flipping out because their nine year old was counting on their fingers.

"I count on my fingers," I told the parent.

The parent was flabbergasted. And complained to my principal that I wasn't qualified to teach math.

My principal told her to ask me for a copy of my M.Ed. thesis, which was on Teaching Metacognative Methods in Early Mathematics Education. Such methods include counting on your fingers. :D

Have you encountered touch math before? That's another one I use all the time.

(here via the Fat Doctor)

Stephen said...

I mentioned tactile feedback toward the end of Part One (the 2nd part).

Some nights when doing astronomy, and i want to know the angle between (for example) 15 degrees and 285 degrees, i'll do touch finger math. It is dark, and i'm looking through the eyepiece anyway. So the answer to the above is 360 - 285 + 15 = 90. Since i only have two hands, i remember each of the hundreds digits.