Tuesday, June 20, 2006

Finger Arithmetic Part Five

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

In Part Three, we introduced the idea that sometimes you want to add something, but you have no fingers left to add. This part does that for the thumb. Here, we add five when the thumb is already set.

The first example is adding seven plus five. First, set seven. Do that by starting with a fist on both hands, adding two fingers to the right hand, then adding the right thumb. Now we want to add five. You want to add a right thumb, but your right thumb is already set. To do this, remember that 5 + 5 is the same as 5 + (10 - 5), which is rearranged as 5 - 5 + 10. Still have zero / seven on your hands? Good. Subtract five by tucking the right thumb down. Add ten by adding a finger to the left hand. Look at your hands. Read twelve.

The next example is adding six and five. First start with both fists. Set six on the right hand by adding a finger and thumb. Add five by subtracting the right thumb, and adding a finger on the left hand. Read the result: eleven.

The final example is adding nine and five. Start with both fists. Add all fingers and thumb on the right hand for nine. Subtract the right thumb and add a finger on the left hand. Read fourteen.

All examples: 5 + 5, 6 + 5, 7 + 5, 8 + 5, 9 + 5.

During the week, go over the previous lesson's examples. Stick to short practices every day. You don't have to do all the examples from all the lessons in one go. But you should sneak in all the examples for all the lessons over the course of the week. And every day should have this newest lesson.

The next lesson will get you started on single digit addition. It won't be the last word there, however. It seems that there is always something more to say.

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