General Source of Computational Methods, Volume 2

Page 3

When meeting six, advance twenty.
Three, one, thirty-one.
Three, one, thirty-one.
When meeting three, advance ten.
Three, one, thirty-one.
When meeting six, advance twenty.
These rhythmic mnemonics, known as "Kou Jue," were chanted aloud while moving beads on the abacus to ensure accuracy and speed.

Suppose a person borrows a Principal Silver original: 本銀 (běn yín) amount of 258 taels original: 兩 (liǎng) and 2 mace original: 錢 (qián). Every year, an interest of 4 This "4" refers to a rate of 4 mace of interest for every tael of principal, essentially a 40% annual interest rate. is added for repayment.
Question: How much interest silver is owed?

Answer: 103 taels, 2 mace, and 8 candareens.

The method states: Set the Principal Silver as the Dividend original: 實 (shí); the quantity being operated upon and use the interest of 4 mace as the Multiplier original: 法 (fǎ). Multiply them together to reach the answer. Positioning the decimal is performed as previously described.

The Multiplier multiplies the figures.

Dividend	Meaning	The Call	Result	Removal	Positioning	Total
Tail	Silver	Four, Four	Add 8 to the position below		Correct	This is the mace; multiply by moving forward as described.
	Designation	Eight, Four	Thirty-two	Change 8 to 3, add 2 to the position below	Taels	The sum is reached.
						Above the multiplier, for every tael, add four; stop at the tael unit. The next position down is the mace.
					Candareens	Discussion

The table illustrates the manual steps on the abacus. For example, "Eight, four, thirty-two" refers to multiplying 8 taels by the rate of 4. On the abacus, the 8 is replaced by 3, and 2 is added to the column to the right, representing the result 3.2.