1. Why Does Asking "What Time Is It?" Reduce the Soba Bill by One Coin?
In an Edo-period soba shop, a customer finishes his meal. The price is 16 mon. A mon was a unit of currency in the Edo period. [1] The customer places coins one by one on his palm, counting aloud: "One, two, three..." When he reaches eight, he asks, "What time is it?" [7]
The soba seller replies, "It is nine." The customer then continues, "Ten, eleven, twelve... sixteen, thank you," and leaves the shop. [7] If you count the coins, the trick becomes clear. He placed eight coins for the count of one through eight. The number "nine" was replaced by the seller's reply, so he did not place a coin for it. He then placed seven coins for ten through sixteen. The total is 15 coins, which is one mon less than the 16 mon price. The joke is that one coin disappears while everyone is distracted by the counting voice. [7] But what time does "nine" actually mean?
2. What Does "Nine" Mean? How Edo People Told Time by Bell Counts
People in the Edo period called time by the number of bell strikes at temples. Midnight (12:00) was called "nine." At 2:00 AM, it was "eight," and at 4:00 AM, it was "seven." Every two hours, the bell count decreased by one. At noon (12:00 PM), it returned to "nine." [6]
Applying this rule, "four" corresponds to around 10:00 AM. The sequence goes from nine down through eight and seven to four, then returns to nine. When the soba seller says "It is nine," it is either midnight or noon. The customer had counted up to eight, so the next number is nine. The reply matches the count perfectly. The story uses this coincidence. [6] So, what reply did the man who copied the trick receive?
3. What Happens When the Copycat Customer Hears "It Is Four"?
A man who saw this trick thought it was clever and decided to copy it. He went to another soba shop, counted to eight, and asked, "What time is it?" [6] The reply was "It is four." It was not nine. The man had to restart counting from "five, six, seven, eight..." [6]
If we track the coins, he placed eight coins for one through eight. Then he counted from five to sixteen, placing 12 more coins. The total is 20 coins, which is 4 mon more than the 16 mon price. However, the amount lost varies by performer; 4 mon is just one example from commentary. [6] This story is performed as "Tokisoba" in the Kanto region and "Tokiu-don" in the Kansai region. [6] But what was the value of a 16-mon bowl of soba to Edo people?
4. Why Was a Bowl of Soba 16 Mon? Two Theories Behind "Nihachi Soba"
Soba in Edo was also called "Nihachi soba." There are two theories for the name. One is the "price theory," suggesting it comes from 2 times 8 equaling 16 mon. The other is the "ratio theory," suggesting it comes from a mix of 80% buckwheat flour and 20% wheat flour. It is not clear which is correct. [4]
One clue is the late Edo-period encyclopedia "Morisada Mankō." It states that in Edo, Kyoto, and Osaka, both soba and udon were called "Nihachi" and cost 16 mon. Since udon is made only of wheat flour, the 8-to-2 ratio theory is hard to explain, making the price theory more likely. [5]
The price of 16 mon lasted for over 100 years, from 1744 to 1860. [4] Because the price stayed the same for so long, many listeners would have known it. That is why the trick of saving one mon was funny. [4] So far, we have discussed small coins called mon. How different is the larger unit of money called ryo? Before that, let's look at a famous math puzzle from rakugo.
5. How Do Three People Each Lose One Ryo in the Rakugo Story "Sanpo Ichiryō Son"?
"Sanpo Ichiryō Son" (Three Parties Lose One Ryo) is a rakugo story where money math becomes a joke. An Edo man drops a wallet with 3 ryo. A finder returns it but refuses to take the 3 ryo, leading to a quarrel. [9]
Ooka, a magistrate, steps in. He adds his own 1 ryo to make 4 ryo and gives 2 ryo to each man. [9] The two men expected 3 ryo but got 2, so they each lost 1 ryo. Ooka paid 1 ryo, so he also lost 1 ryo. Since all three lost 1 ryo, it is called "Sanpo Ichiryō Son." [9]
What was one ryo? In this example, one ryo of gold is one Keicho koban, weighing about 17.8 grams. It is about the weight of 18 one-yen coins. One quarter of a ryo is one bu, and one quarter of a bu is one shu. [10] This story is said to be based on the Chinese book "Tang Yin Bi Shi," and it is likely that Ooka did not actually judge this case. [9] It is best enjoyed as math within a story. So, how far apart are 16 mon for soba and one ryo?
6. How Many Mon Equal One Ryo? Comparing Small Change and Gold in Edo Money
In the late Edo period from 1842, the official exchange rate set one ryo at 60 monme of silver or 6,500 mon. [2] Dividing by the 16-mon soba price, one ryo is about 406 bowls of soba (6,500 ÷ 16 = 406.25). [2]
However, one ryo was not always this number of mon. It changed depending on the period and exchange rates. [2] In the rakugo story "Shibahama," a fisherman finds a wallet with 42 ryo. [8] At the rate of 6,500 mon per ryo, 42 ryo is 273,000 mon, which is about 17,000 bowls of soba (this is just a calculated figure). [8]
In modern money, the Currency Museum FAQ states that one ryo is about 80,000 yen based on rice prices, or about 410,000 yen based on a carpenter's wage. The value changes greatly depending on the measure used. [3] The one mon saved in "Tokisoba" and the 42 ryo in "Shibahama" feel very different in size, even though both are rakugo stories. [8]
7. How Can You Investigate Further? Try the "Tokisoba" Counting Trick with Coins
Things you can do today: Prepare 16 ten-yen coins or glass beads. Try copying the counting method from "Tokisoba." Place one coin for each count from one to eight. Do not place a coin for nine. Then place coins for ten through sixteen. How many coins do you have in total? Next, try changing the reply to "four" and count from five to sixteen. [7]
Things you can do when you go out: Listen to and compare rakugo performances of "Tokisoba" and "Sanpo Ichiryō Son" at libraries or via video streaming. Pay attention to how the rhythm of counting and the way the lost amount is described differ between performers. [6]
Official information: The Currency Museum of the Institute for Monetary and Economic Studies at the Bank of Japan has a page titled "How much is one ryo from the Edo period today?" It explains the conversion methods in detail. [2]