In the evening, Yuwen Wen, who had just finished the military discussion, entered the city again. He stayed in the Woyang City, ate a few cakes and drank a few bowls of porridge, and continued to pick up the guests... When meeting the guests, the guests he wanted to meet this time were civilians, and the matters he wanted to discuss were both public and private.

Wang Yue and several Huangzhou merchants waited in the Woyang Office for most of the day. At this time, they finally met the King of Xiyang (the big boss), so they all had a stack of thick information and prepared to report to Yuwen Wen.

Yuwen Wen is very busy, so he has no time to talk nonsense. His opening remark is "The principal is about to come in, and the next step can be started."

The so-called "principal" means that when Yuwen Wen met with the children of powerful men from all over the country in the afternoon, he proposed to "borrow" from various clans. These clans must lend materials of varying amounts to the government army within five days. This is the "principal".

Yuwen Wen got this amount of materials that were expected to be discounted by more than 1.5 million guan, which could be used to supplement military supplies, but there are two ways to use them.

The first method is to directly use these materials as military supplies and be simple and straightforward; the second method is "capital operation". After a series of operations, two cents can be spent at least three cents.

The second method sounds good, but it is risky to implement, that is, once you encounter "irresistible factors", you may mess up and not be as safe as the first method.

After comprehensive consideration, Yu Wenwen chose the second method, which is to deposit the borrowed materials into the Rixingchang Cabinet. On the premise of ensuring military supplies, Rixingchang Cabinet and others can make a fortune.

On behalf of the Huangzhou General Administration Office, he borrowed 10% of the interest from local tyrants and deposited 15% of the interest in Rixingchang Cabinet. Rixingchang Cabinet was lending 20% ​​of the interest, lending to local workshop owners, allowing them to expand production and recruit more people.

We also need to lend to Xinwu Fort owners in various parts of Huaixi to give them sufficient material support to successfully complete the autumn harvest. The food harvested in these places will be the key to ensuring the marching and combat of Lingnan Road.

Yuwen Wen’s capital operation is to maximize the effect of this material.

He put down the information and asked, "Can 20% of the loan interest ensure that Rixingchang does not lose money? Can the borrower still not lose money after paying back the money?"

Wang Yue replied after hearing this: "Please rest assured, after calculating this interest, there will be no loss, and there will be even a slight surplus."

"The formula is quite complicated and has been updated again, so you can't be careless."

"Don't worry, the shopkeepers can already use the new formula skillfully, and there is absolutely no problem with the calculation results."

Yuwen Wen picked up the information again: "There is nothing absolute in the world."

"What the king said is that the people are abrupt."

As soon as Wang Yue finished speaking, Yuwen Wen looked at someone beside him and asked, "Tell me, what about the loans in Huaixi."

"Yes, king..."

Following Wang Yue, I met several merchants from King Xiyang and began to introduce the details of this capital operation to Yuwen Wen. The "formula" they mentioned is a magical financial management formula: the interpolation formula.

To be precise, it is the formula for interpolation of three times inequality.

This formula was proposed by Liu Zhuo, one of the two Lius. It was originally used to compile the astronomical calendar. Yuwen Wen knew nothing about it, so Liu Zhuo also explained it specifically.

Interpolation, also known as the technique of attacking differences, is the "insufficient technique" in the Han Dynasty's work "Nine Chapters of Arithmetic", which is equivalent to the one-time difference interpolation method (linear interpolation).

Since the Han Dynasty, astronomers of all dynasties have tried to compile a set of the most accurate calendars. They regard the visual movements of the sun and the moon as uniform speeds. This is of course simpler to calculate the movements of the sun and make up the calendar, but inaccurately.

Zhang Zixin, an astronomer in the late Yuan and Wei dynasties, found that the sun runs slowly after the vernal equinox and fast after the autumnal equinox.

This fact prompted astronomers to create new ways to calculate problems such as the Sun's movement.

Liu Zhuo, who is famous for literature but is also proficient in mathematics and astronomy, first used equally spacing quadratic interpolation formula in the astronomical calendar to improve the calculation accuracy based on Zhang Zixin's theory and the first interpolation method in the Zhouren Academic Summary.

When Liu Zhuo calculates the direction of the day, month, and five stars, he uses equal-space quadratic interpolation method, using time as independent variables, and divides the year into 24 equal time intervals, each interval is regarded as the length of time between the two solar terms.

Liu Zhuo believed that the sun's movement was uniformly accelerated, so the calculation of the sun's apparent direction degree should be done by equally spaced quadratic interpolation.

Yu Wenwen, who had basically forgotten his mathematical knowledge, could not understand what the formula calculated by Liu Zhuo meant, but he questioned Liu Zhuo's definition of "the time intervals of twenty-four solar terms in a year are equal."

The scholars gathered in Xiyang, some who are proficient in astronomical calendars, have put forward their own opinions on this. After countless academic debates, Liu Zhuo realized that his views might be wrong, so he improved the calculation formula of the interpolation method again.

The equally spaced quadratic interpolation formula evolved into the "unequally spaced quadratic interpolation formula".

As a result, Liu Zhuo revised the new calendar he had worked hard to compile again. Yu Wenwen was not interested in this "unequal spacing quadratic interpolation formula" because even if he understood it, he did not intend to participate in the compilation of the calendar.

However, after thinking about this formula, the shopkeeper Wang Yue found that the interpolation method had other uses, that is, financial management and financial management (capital operation), which maximized the benefits of an investment.

To describe it in more ‘professional’ terms, it means to calculate the rate of return by interpolation.

Example 1: Calculate the discount rate. Zhang San, a rich man, wanted to save money at Rixingchang Guifang to earn interest. His idea was to deposit 5,000 guan. In five years, there must be 7,500 guan. So how much deposit interest should be achieved to achieve his financial management goals?

Example 2: Calculate the interest calculation period: Li Si, a resident of Xiyang City, has an idle courtyard on hand. He has two choices: one is to rent the courtyard, and the other is to sell the courtyard directly.

The yard is sold at a price of 20 jin according to the market. If the yard is rented out, three jin of rent will be charged at the beginning of each year. Assuming that the income from the sale of the house is deposited into the counter house, the interest will be 10%, and the cost of the house repair in the yard will not be counted.

In this case, how many years does Li Si have to rent the yard to make the rental income equivalent to the income from one-time house selling (including interest on savings)?

Example 3: Calculate the investment payback period: A businessman Wang Wu has to invest in the construction of a papermaking workshop with his own funds of 10,000 yuan, with a construction period of three months and eight years of operation.

After the paper mill is put into production, the net cash flow generated in the first four years was 4,000 guan, 3,000 guan, 2,000 guan and 4,000 guan in succession.

The net cash flow generated each year in the next four years is 3,000 jin. So how to calculate the throwing and recovery period including the construction period and the investment recovery period not including the construction period?

These three problems can evolve into more problems, and can be solved by quotient accumulation, but ultimately, it depends on empirical calculations. Once you encounter "investment projects" with complex situations and a lot of variables, even a profitable businessman may not be able to understand them clearly.

With the interpolation method, you only need to substitute the interpolation formula and you can calculate the result immediately, which is simple and clear.

For Rixingchang Cabinet, which uses depositors to make profits by raising funds, the interpolation formula is a powerful tool for investment, financial management and capital operation.

The formula for equidistant quadratic interpolation proposed by Liu Zhuo is based on the improved formula for equidistant quadratic interpolation. After actual operation and inspection by the shopkeepers, it was found that it was indeed "magical".

The "unequal three interpolation formula" derived by Liu Zhuo and other scholars made Rixingchang feel like a tiger when he was in lending and investing in business. The interpolation formula originally used to calculate the astronomical calendar has become Yuwen Wen's magic weapon for profit.

This is the power of mathematics. Yuwen Wen wants to operate capital this time. Eat more fish, and the confidence comes from the interpolation formula that has been tested by practice.
Chapter completed!