ABACUS: MYSTERY OF THE BEAD
The Bead Unbaffled - An Abacus Manual
Patterns in Kojima's Method for Multiplication
An abacus is not a calculator. Rather, it's a tool for recording answers. This becomes particularly evident when doing problems of multiplication. Once learned, the technique of recording answers onto the correct rods makes doing multiplication virtually foolproof.
Kojima's technique is so effective in part because we're taught to place product answers right next to the numbers in the multiplicand. This ensures that the correct numbers are always added to the correct rods.
Kojima always sets the multiplier to the left of the multiplicand. I will do the same in each example.Example: ab * c = xxx c * abc * b|xx c * b = xx, clear b c * a|xx c * a = xx ans: |xxx Example: ab * cd = xxxx cd * abc * b|xx c * b = xx d * b| xx d * b = xx |xxx interim answer, clear b c * a|xx c * a = xx d * a| xx d * a = xx ans: |xxxx Example: abc * de = xxxxx de * abcd * c|xx c * c = xx e * c| xx d * c = xx |xxx interim answer, clear c d * b|xx c * b = xx e * b| xx d * b = xx |xxxx interim answer, clear b d * a|xx c * a = xx e * a| xx d * a = xx ans: |xxxxx Example: abc * def = xxxxxx def * abcd * c|xx d * c = xx e * c| xx e * c = xx f * c| xx f * c = xx |xxxx interim answer, clear c d * b|xx d * b = xx e * b| xx e * b = xx f * b| xx f * b = xx |xxxxx interim answer, clear b d * a|xx d * a = xx e * a| xx e * a = xx f * a| xx f * a = xx ans: |xxxxxx
▪ Multiplication Examples
© September, 2007
Totton Heffelfinger Toronto Ontario Canada