Subtracting Two Numbers Directly


Subtracting two numbers directly is the opposite of adding two numbers directly.  When subtracting the user clears, or removes, beads from the horizontal bar.  

In the problem 9-3=6 the user sets 9 in the ones column.  

9 is set on the abacus.

She then asks, "Can I clear 3 directly?"  Since she can, she moves the three 1-beads away from the horizontal bar.  

The abacus then reads 6 as shown in the picture below.

The abacus has 6 set, a 5 bead and a 1 bead in the one's column.

Review the PowerPoint "Subtracting Directly" for practice on this type of computation.