# Chiu Chang Suann Jing/Examples/Example 1

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## Example of Problem from

## Example of Problem from *Chiu Chang Suann Jing*

Two and a half piculs of rice are bought for $\dfrac 3 7$ of a tael of silver.

How many piculs of rice can be bought for $9$ taels?

## Answer

Let $x$ be the required quantity.

- $\dfrac x 9$ piculs can be bought with $1$ tael.

Hence $\dfrac x 9 \times \dfrac 3 7$ can be bought for $\dfrac 3 7$ of a tael.

That is:

- $\dfrac x 9 \times \dfrac 3 7 = \dfrac 5 2$

and so:

- $x = 9 \times \dfrac 5 2 / \dfrac 3 7 = 52 \frac 1 2$

$\blacksquare$

One picul, apparently, is equal to about $65$ kilograms.

## Sources

- 2008: Ian Stewart:
*Taming the Infinite*... (previous) ... (next): Chapter $3$: Notations and Numbers: Brahmagupta, Mahavira and Bhaskara