Saturday, June 17, 2006

Finger Arithmetic Part Four

Continuing finger arithmetic from Part Three. This one is called Part Four. It is the fifth part in the series.

Bigger numbers are added to small numbers. It's an easy lesson that introduces thinking of bigger numbers as the sum of two smaller numbers. One of the smaller numbers is always five. In fact, when you set one of these numbers on a hand, the thumb is the five, and the fingers represent the other small number.

Let's say you have one, and want to add seven. For the moment, set seven on one hand. Make a fist. Add two fingers. Add the thumb. Seven is five plus two. So we can add these parts one at a time. Here are the steps. We're adding one plus seven. Set one by making a fist on the right hand, then add one finger. Add the 'two' of the seven by adding two fingers. Then add the five of the seven by adding the thumb. Read the answer. Uhm, let's see. There's a thumb. There are three fingers. That's eight.

Now we'll add three plus six. Set three by making a fist and adding three fingers. Six is five plus one. Add one by adding a finger. Add five by adding a thumb. Read the answer. Nine.

Try two plus seven. Set two. Add the two. Add the five. Read the result (nine). You did say it out loud, right?

Three plus five. Make a fist. Add three fingers. Add the thumb.

All of the examples: 0 + 5, 0 + 6, 0 + 7, 0 + 8, 0 + 9, 1 + 5, 1 + 6, 1 + 7, 1 + 8, 2 + 5, 2 + 6, 2 + 7, 3 + 5, 3 + 6, 4 + 5. Try them all.

Keep practicing Part Three during the week. It takes a bit for the Five's Complements to stick in your head. We'll need to expand on this idea soon. We're trying to keep it down to one new idea a week. However, you need to remember all the old lessons to get it all together.


Glenn in Minnesota said...

Hi Steve,

Just stumbled across your blog. How's the birding these days?

Stephen said...

It was kind of an odd season this spring. I did get to the boardwalks in Ohio to see a dozen warbler species...