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Hi, Iím Paul from Guruparents. Welcome to part 5 of our introduction to the abacus.
In previous videos Iíve shown you how to add by 1, 2, 3, 4 and 5 and today weíre going
to look at adding by the remaining numbers.
And youíll be pleased to discover that adding by the larger numbers is actually quite simple.
Iíll show you how now.
Iíll start by showing you how to add by 9. On some occasions, rarely, youíll be able
to do this by just moving up the beads in one column.
So if we start with zero on the soroban, as we have now, adding 9 is simply a case of
doing that in that first column.
But what about now if we wish to add 9 more?
Well, as in previous videos weíre going to have to move to this next column ñ the tens
column.
And Iím going to be adding 1 into that tens column ñ which means that Iíll be adding
10.
10 is 1 more than the 9 that I wish to add, so firstly I subtract 1 from this column,
so when I add 1 to the tens column, the net result is Iíll have subtracted by 1 and added
by 10: Iíll have added 9.
And as for the sum ñ what have we got left? Weíve got a 1 in this column, 5 and 3 are
8 in this ñ and so weíve got 18. And thatís correct because 9 + 9 = 18.
Now letís start again with zero on the soroban and this time weíll add by 8.
As was the case last time, adding 8 to 0 is simple enough ñ we simply move 8 beads into
place.
And again if weíre going to add a further 8 to this weíre going to have to make use
of this next column.
This time if weíre adding 10 itís going to be 2 more than the 8 we wish to add, so
I firstly subtract 2 and then I add my 10 for a net result of adding by 8.
And what have we got on the soroban? 1 here, 5 and 1 ñ thatís 6. 16 ñ and 8 + 8 = 16.
So letís move on to 7.
For a change Iíll start with 2 on the soroban. Whatís 2 + 7 ñ have we got enough beads
to use the first column only?
Well yes we do, because weíve got 2 here and 5 here. And 2 + 7 is 9.
Now to add 7 further to 9.
Once again, weíre going to have to add 1 into the next column.
Adding a 10 means weíre adding 7 more than the 3 we wish to add. So firstly, subtract
3, then add 10 for a net result of having added by 7.
And what have we got left on the soroban ñ 1 here, 6 here: 7 + 9 = 16.
Lastly, letís add by 6.
This time Iíll start with 3 on the soroban.
First of all, as with previous examples, we can do it directly ñ by adding a 1 and a
5, thatís adding 6.
But now to add a further 6 weíre going to have to make use again of the next column.
This time, the 10 that we add is going to be 4 more than the 6 we wish to add.
So firstly, I subtract by 4 and then I add my 10 to the next column, for a net result
of having added 6.
And what are we left with on the soroban?
Well, we have a 1 here and a 5 here ñ thatís 15.
So 6 + 9 = 15.
I should say 9 + 6 = 15.
All right, letís move on to do some practice.
Hereís the sum that Iím going to do:
94,219 + 79,866
So, firstly weíre going to be using this column here.
So, weíll start by setting up the first number ñ with a 9 in that first column.
Into the next column we wish to add a 4.
2 in the next column ñ there we go.
1 in the next column.
And all of the beads will be in play for the last column.
Now, letís add our number to this.
So firstly weíre going to be adding 7 to this column here.
We canít do it directly because we havenít got enough beads available so weíre going
to have to add 1 to this column here which will be adding 10 and thatís 3 more than
the 7 that we wish to add.
So firstly I subtract 3, then I add my 10 ñ which is adding 1 to that column. And there
we have added by 7.
Moving along to this column. We wish to add by 9.
Again, we donít have enough beads available so weíre going to have to move into this
column.
But I only wish to add 9, not 10, so firstly, I subtract 1, so that when I then add my 10
weíll have added by 9.
Next, to add 8 into this column. Have we got enough beads available?
We donít quite ñ weíve got 2 here and 5 here ñ thatís 7. Not quite enough.
So, instead weíre going to have to add 1 to this column. Adding 1 to this column means
that weíre adding 10, which is 2 more than the 8 that we wish to add.
Subtract my 2, then add my 1 here, for a net result of adding 8.
Moving on into the second last column, and this time we can add directly.
Weíre adding 6 and we can just simply pinch these here. 5 and 1 ñ and weíve added 6.
Into the last column. To add 6 to this ñ well we donít have enough beads.
So, instead we firstly subtract 4 then add 1 to this column for a net result of adding
by 6.
And, what are we left with?
Well, weíve got a 1 in this column here.
Weíve got 2 and 5 make 7 here.
4 here.
Weíve got nothing here.
Weíve got 3 and 5 make 8 here.
And we have 5 here.
And so 94,219 + 79,866 = 174,085.
So there you have it, over the course of these 5 videos Iíve shown you how to add by all
of the different numbers on the soroban.
However, there is just one more thing to cover off.
Some of the situations that can occur in addition are a little bit more complex than what weíve
shown so far.
So stay tuned for the sixth and final video, where Iíll take you through the most challenging
examples, after which youíll be a fully-fledged master of addition on the soroban. Iíll see
you then.