Sun Zi's Mathematical Classic

One cubic inch|original: 寸; cun, approximately 3.1 cm in the period of jade weighs twelve taels|original: 兩; liang, approximately 37 grams.
One cubic inch of copper weighs seven and a half taels.
One cubic inch of lead weighs nine and a half taels.
One cubic inch of iron weighs six taels.
One cubic inch of stone weighs three taels.

Whenever using the method of calculation|original: 筭; suàn, referring to the use of counting rods, one must first recognize the positions:
Units are vertical, tens are horizontal.
Hundreds stand [vertical], thousands lie [horizontal].
This alternating orientation—vertical for odd powers of ten and horizontal for even—was a brilliant ancient safeguard to ensure that if rods shifted slightly, the calculator could still distinguish between, for example, 11 (horizontal-vertical) and 2 (two verticals).
Thousands and tens mirror each other; ten-thousands and hundreds correspond.

In the general method of multiplication:
Place the numbers in two rows, one above the other, and observe their positions.
If the top position represents tens, step to the tens; if it represents hundreds, step to the hundreds; if it represents thousands, step to the thousands.
This describes the alignment of the multiplier and multiplicand on the counting board.
Use the top value to operate on the bottom.
The resulting numbers are arranged in the middle row.
If a value reaches ten, move it to the next place [carry]; if it does not reach ten, leave it as is.
When multiplication by a digit in the top row is finished, remove it.
When the multiplication of the lower positions is finished, shift all rods back.
Six is not accumulated; five is not single.
This mnemonic "Six is not accumulated, five is not single" refers to rod notation: instead of using five individual rods to represent the number 5, a single rod is placed in the opposite orientation to represent a value of five, and 6 is shown as this "five-rod" plus one unit rod.