This is a Japanese abacus.  There are 1 bead at the top and 4 beads at the bottom.  There is a bar in between the beads, when a clear button is clicked, all beads will be separated and cleared.  If there are no beads touching the bar, that is ZERO. 

This video is about how to represent 1 to 10 in abacus.

What is imagery of Abacus?

We are going to use different images to represent numbers from 1 to 9 in Abacus.

Do you know there is a friend for each number from 1 to 9? You may pair them up and it is easy to remember if you follow the previous lesson. 

In this lesson, I am going to explain who is the friend of the number 1 to 9.  It will be very useful in abacus if you can remember each number's friend.

In the last lesson, we have already learned the basics of how to add and subtract in the abacus. In this lesson, I will explain more details about how to add and subtract from 1 to 4 in Abacus.

This lecture is about how to add and subtract numbers from 1 to 9.  It also includes the top bead - "5".  It is not difficult as long as you have idea of how to represent 1 to 9 in Abacus.   Please do the exercise that I provided below.  :)

There are 3 Rules for Addition.  If you cannot add by the normal way, Addition Rules will be needed to apply.  Which rule is going to apply?  It all depends on the situation.   I will explain it one by one in the following lecture.

This is the first rule that we use if the normal addition cannot work.   

The First Rule is "Minus Friend, Left Hand Plus One"

This is the Second Rule that we use if the normal addition and First Rule cannot work properly.

The Second Rule is "Pull Down Friend"  

This rule can only be applied for 1, 2, 3, 4.    If 5 is down, we cannot "Pull Down Friend", right? :)

This is the Third Rule that we would use if the normal addition, First Rule, and Second Rule cannot work properly.

The Third Rule is "Push Itself Upward, Left Hand Plus 1"

This rule can only be applied when 5 is down.  If 5 is on the upside, we cannot "Push itself upward", right?

This is really a good practice to test whether you get familiar with all the addition rules.

If normal subtraction doesn't work, you may use subtraction rules.

There are two rules for subtraction,

1. Push Friend Upward

2. Left Hand Minus 1, Add Friend

Both rules need Friends to complete the subtraction.

This is the 1st rule for subtraction --- "Push Up Friend"

This subtraction rule can be applied:

1. When you cannot subtract a number from the normal situation

(Please review the normal subtraction from 6, 9, and 10 if you forget the normal situation.)

2. You want to subtract a number that is between 5 to 9.  Otherwise, you are not able to push your friend upward,  right?  :)

This is the 2nd rule for subtraction --- "Left Hand Minus 1, Add Friend"

You may apply this subtraction rule when:

1. Normal subtraction is not working.

2. The subtracted number is greater than 10.  Otherwise, you may not minus 1 by using your left hand.