The carpenter soon came, a black-faced man in his forties, and his clothes were still on, at least much better than Chen Xu's family before, and he was a little nervous and apprehensive when he saw the newly appointed Lord Lidian for the first time.

"Craftsman Liu Erwa has seen Lord Lidian!"

Chen Xu's legs were weak and he almost went up with a pestle, and a half-old man turned out to be called Erwa.

"Excuse me, I have designed a new kind of arithmetic, you can help me create it!" Chen Xu took the carpenter's arm and pulled it to the front of the stone slab, and carefully explained the structure of the abacus and the size of each part one by one, "Do you understand?" ”

"Got it, got it!" The carpenter nodded again and again, although he had never seen it, but after all, he was a carpenter with professional qualifications recognized by Daqin, and he knew what to do at a glance with a simple structure.

"Because the time is urgent, just use bamboo to make it, the sooner the better, can it be done in an hour?" Chen Xu breathed a sigh of relief.

"It doesn't take an hour, it takes half an hour!" The carpenter nodded easily.

"That's good, do it!" Chen Xu waved his hand, and the carpenter hurriedly left.

"My lord, how should I use this calculation?" Niu Quan looked at the abacus pattern on the slate and stared at it for a long time before asking suspiciously.

"Don't worry, I'll think about the mantra first!"

Chen Xu squatted down again, picked up a piece of charcoal and began to write and draw on the slate, muttering in his mouth, "One up, two up, two...... Five to four...... Two to eight into one...... Seven on two to ...... Go...... A few ...... to Nima"

Chen Xu wrote out a long row of messy Arabic numerals as if chanting a scripture, and kept pulling down strands of hair.

Niu Dashi was no longer surprised by the words written by Chen Xu that seemed to be crickets, and he could recognize a few, but Niu Quan was completely stunned, but he didn't dare to disturb Chen Xu, so he could only stand behind his back and stare at a pair of eyes as if reading a book from heaven.

The abacus formula Chen Xu learned when he was a child, but it was limited to addition and subtraction, and after a decade or two, it had already been returned to zero in his memory.

But even so, as a great quintessence of the country, under his slow recollection, more than ten minutes passed, and the simple addition formula was still made by him, and he could dial it out next to each other just by waiting to get the abacus.

Subtraction is a bit more troublesome, but with the addition formula, it can still be deduced, as for multiplication and division, that ...... It's so hard that he can't summarize his current state in a few months, and he can't use it yet.

An hour passed quickly, and Chen Xu's subtraction formula was almost smooth, when the carpenter came over panting with an object.

"My lord, the plan is ready!"

"Good!" Chen Xu stood up happily, but then his eyes were black and almost hit the stone slab, and his body shook a few times and was quickly supported by Niu Dashi.

Nima has been squatting for a long time and is a little anemic.

Looking at this bamboo abacus that is two feet long and one foot wide, Chen Xu picked it up and shook it a few times, and then used his fingers to flick the abacus beads made of bamboo up and down a few times, although there were some burrs and jams, but they basically met the requirements.

"Niu Quan, I'll teach you how to use this calculation, you have to remember these formulas!"

Chen Xu said and put the abacus on the stone slab, pointed to the eight wooden stalls on it and said: "The first one represents a single digit, the second one means ten, the third one represents a hundred, and so on, the rest represents thousands, ten thousand ......, the four beads below represent one, two, three, four, and one bead above represents five, then one is one, and the formula is called one and one on the ......."

Chen Xu said and pushed up an abacus bead in the single digit with a snap.

"Two is two, and the formula is called two on two......"

Chen Xu said, his fingers moved, and with the crackling sound, the numbers from one to nine were demonstrated next to each other.

"Now let's start adding, one plus one, one plus two...... If you are full of five, you will go to the next ...... four"

The addition of the abacus is actually very simple, as long as you memorize the formula.

With Chen Xu's explanation and demonstration, Niu Quan was dumbfounded, his mouth opened wide, and his eyes were not blinking.

He is also proficient in superficial mathematical addition and subtraction, and he uses the calculation chip to count addition and subtraction on weekdays, and he does not feel complicated, but at this time, when he saw the new calculation chip designed by Chen Xu that he had never seen, while memorizing the formula, his heart was already like turning over the river and the sea.

"Niu Quan, you can try it!" Chen Xu stood up and pointed to the abacus and said.

"Okay, let the subordinates try it!" Niu Quan squatted down excitedly, and while reciting the mantra while dialing the abacus, Chen Xu was beside him to guide and remind, after more than ten minutes, Niu Quan had been able to apply the addition completely, although it was relatively slow, but basically there was no mistake.

"Okay, you take out the tax and grain roster you received yesterday and calculate it and see if there are any errors!" Chen Xu commanded.

"Hey, good!" Niu Quan hurriedly went to the warehouse and took out a roll of bamboo slips, spread it out on the stone slab, and began to accumulate and settle against the numbers recorded on each bamboo slip...... Uh, my lord, can you give this calculation a name and simply call it Chen's calculation! ”

"No, just call it an abacus!"

"Okay, calculate the data, take stock of the right and wrong, the word abacus is appropriate!" Niu Quan hurriedly patted his ass.

Chen Xu silently mourned for a few seconds in his heart for the mathematician who invented the abacus hundreds of years later, sorry for that old ancestor...... uh, no, Lao Tzu crossed over before the Han Dynasty, he should be their ancestor.

"The abacus is lightweight, easy to use, but you have to memorize the formula, and there is a subtraction formula behind, you can be proficient in the application, if you don't understand it, you can ask me, I asked the carpenter to build a few more abacus and send it over, and when the grain collection team comes back, you want to teach the tax collector to use, and there must be no mistakes in the summer grain!"

"Don't worry, my lord, Niu Province will have it!" Niu Quan nodded hurriedly.

Chen Xu then told the carpenter to make a few more bamboo abacus, and at the same time asked him to use wood to create a good-looking and delicate one, when he was fine, he could calculate the multiplication and division formula, and recommend it to the county order Jiangbei Pavilion in a few days, maybe he could get some benefits.

Soon several days passed, as the threshers in various villages began to be manufactured in large quantities, the news fed back by several pavilion chiefs seemed that the summer grain harvest had entered a very good state, and the grain collection team also kept cattle and horses every day, and piles of grain were pulled to the warehouse in an endless stream.

Chen Xu's heart also slowly relaxed, and every day he had nothing to do, he followed Old Man Chen to learn Qin Law, and took the time to practice abacus, or he rode a hairy horse with Niu Dashi to walk around the town to familiarize himself with the territory, and at the same time planned where to start to solve the poverty in Qinghe Town after the end of the farming, so the life was idle and busy!