I just never knew. I really didn't.
And in case there is someone else out there who doesn't (and would like to know), here I am.
We've used ours often enough, that's true. It has hung out on the computer table for years, on and off. Mostly for JumpStart games, and the like. (Sixteen plus seven is what?)
But this is a whole different thing.
This way one can sum up to ten billion, nine hundred ninety-nine million, nine hundred ninety-nine thousand, and nine hundred ninety-nine. More than I've ever needed to add. :)
Here's what I showed my children the other day.
We'll start with the simple stuff.
Let's say... 13 + 5.
We need no more than two digits for this sum, so we'll use the top two rows.
One goes in the 'tens' row, three go in the 'ones' row.
'One' in the tens row (ten), and 'eight' in the ones row makes 18!
* * *
Next comes the more complicated stuff... but when you get this one, you get the whole thing.
18 + 25.
Pretty sure that we'll still be within two digits ;), so we'll stick with two rows.
The same '18'...
Now to add 25.
and now five.
(we made 'ten', so must add that ten to the 'tens' row,
and...three, four, five.
'Four' in the tens row, and 'three' in the ones row.
That makes 43!
129 + 76.
We'll need three rows.
And then one,
(we've now made ten, so we add that 'ten' to the tens row...
and then back to zero with the 'ones' row....
but we've also used all ten of the 'tens' row of beads,
so that makes a 'hundred', so add one to the hundreds row...
and then back to zero with the 'tens' row...)
and then two, three, four, five, six.
Two in the 'hundreds' row,
nothing in the 'tens' row,
and five in the 'ones' row.
129 + 76 is...
205!. : )
Now everyone (er... namely Me) gets to be impressed with themselves because they can easily -and differently- add four billion something to three billion something.
And even something else to that! :)
And being impressed with one's self
is a Very Fine Thing.