Chapter 38: Unified Mathematics, The Nine-Nine Multiplication Table

"Enough. Recognizing numbers and carrying over are just the basics." Lin Xuan set down his water cup, reached out to take the Tablet Computer, and said, "Since you learn so quickly, let's add some spice tonight."

He tapped open the video software on the Tablet Computer.

"Using formal Chinese characters for accounting is a dead thing."

"These ten Arabic Numerals are alive."

"Combined, they can generate infinite variations."

Lin Xuan's finger hovered above the play button.

"Open your eyes wide and watch how people of later generations use these ten symbols to measure heaven and earth."

A cheerful electronic keyboard intro burst through the living room's silence.

Ten colorful cartoon numbers popped up on the Tablet Computer screen.

They had arms and legs, jumping up and down to the music's beat.

A children's chorus came from the speakers.

"One times one is one, one times two is two, one times three is three..."

Lin Xuan pushed the Tablet Computer to the center of the coffee table.

He took a sheet of white paper and pulled the cap off a black marker.

He drew four symbols on the paper: +, -, ×, ÷.

"Once you've learned carrying over, you must also learn to calculate; this is called addition, subtraction, multiplication, and division." Lin Xuan tapped the multiplication sign with his pen tip. "What the video sings is the multiplication table, specifically paired with this cross sign."

Xiao Sizi sat cross-legged on the sofa, staring tightly at the cartoon figures jumping in the screen.

The melody was catchy, the rhythm brisk.

She unconsciously shook her head along with it.

"Three times five is fifteen, three times six is eighteen..."

She opened her small mouth and sang along.

Watching the little girl shake her head and sway, Lin Xuan's lips curved upward.

The song finished playing.

The final line, "Nine times nine is eighty-one," fell.

Xiao Sizi was still unsatisfied.

"This song is wonderful." She clapped her hands. "It is easier to remember than the court's elegant music. Is this the method of later generations for measuring heaven and earth?"

"This is just a basic tool; reciting without practicing is fake."

"Sit closer and watch."

Xiao Sizi shifted her body forward and leaned her head out.

Lin Xuan wrote four numbers on the white paper: 5876.

Aligned below, he wrote: 89.

He drew a horizontal line and added a "×" on the left.

"How long would it take the Ministry of Revenue of the Great Tang to calculate this account?" Lin Xuan asked.

Xiao Sizi thought for a moment.

"We would need to ask an old accountant, take a wooden abacus, and move the beads."

"Two people would verify to prevent errors and omissions."

"About half a cup of tea's time."

Lin Xuan didn't reply; his pen tip touched the paper.

"Nine times six is fifty-four, write four, carry five."

"Nine times seven is sixty-three, add five, sixty-eight..."

Lin Xuan muttered the multiplication table just played.

His pen tip moved swiftly across the paper.

A string of numbers lined up under the horizontal line.

Next, he calculated the tens place.

"Eight times six is forty-eight, carry four..."

Another row of numbers appeared, offset by one position below.

Finally, he drew a horizontal line and added the top and bottom.

His pen tip paused, drawing a black dot.

Lin Xuan read out the final result: "522964, five hundred twenty-two thousand nine hundred sixty-four."

"Fifteen seconds, calculation complete."

Xiao Sizi stared at that sheet of white paper.

No counting rods, no abacus.

Three rows of numbers, top and bottom.

Neatly arranged, with rigorous carrying-over logic.

"Just these few strokes?" She looked up, her eyes full of confusion. "No need to move beads or verify? And thus calculate a large number of five hundred twenty thousand?"

"This is the power of combining Arabic Numerals with the multiplication table."

"As long as you memorize the multiplication of one to nine thoroughly, let alone four-digit numbers, you can even calculate ten-digit numbers multiplied by ten-digit numbers."

"As long as you are given enough paper, you can calculate the answer yourself in half an hour, without a single error."

Above the Sky Screen, Lin Xuan's manual calculation process reflected across Jiuzhou.

Great Tang, Ministry of Revenue Office.

After hearing Lin Xuan's calculation, Tang Jian turned and roared.

"Bring the abacus! Calculate five thousand eight hundred seventy-six multiplied by eighty-nine!"

Three old accountants stumbled out of the main hall.

They held black-wood abacuses in their hands.

They squatted on the ground, their fingers flying up and down.

The beads clashed, making a crackling sound.

This multiplication was huge, requiring repeated carrying.

The old accountant was covered in sweat, muttering to himself.

A while later.

The three stopped.

"Minister... it's calculated." One accountant's voice trembled as he looked at the beads on the abacus. "Five hundred twenty-two thousand nine hundred sixty-four."

Tang Jian's legs went weak.

He stepped back and bumped into the stone pillar behind him.

A long series of complex abacus calculations.

In the hands of a youth from a later age, it became a few nursery rhymes sung by children, plus a few short lines on paper.

In just over a dozen breaths, it solved the half-cup-of-tea's hard work of the Ministry of Revenue accountants.

Dimensional strike.

The word the Sky Screen had used before floated into Tang Jian's mind.

He felt this word was extremely fitting.

Great Tang, Taiji Palace.

Li Shimin looked at that piece of paper.

Rolling in his mind was the Great Tang's massive administrative machine.

Taxes reported from prefectures and counties across the land.

Troops deployed and grain supplies mobilized.

Reported layer by layer, audited layer by layer.

Consuming countless manpower, yet still full of loopholes.

Officials deceiving, accountants embezzling.

All because Arithmetic was tedious, making it hard for others to verify.

If one calculation of military grain went wrong, the front-line army would face starvation and mutiny.

If all soldiers and generals, and all prefectural and county magistrates, understood such concise Arithmetic.

Li Shimin turned.

He strode into the main hall.

"Beat the drums! Summon all officials to court!"

The drumbeats shook the sky.

All civil and military officials, whether on leave or not, rushed to Taiji Palace under the stars and moon.

Inside Taiji Hall.

The lights were bright.

Li Shimin sat on the Dragon Throne, his gaze sweeping over the ministers.

"The numbers and formulas taught by the Sky Screen have all been seen by you, my lords."

"Ministry of Revenue."

Tang Jian stepped forward and knelt prostrate.

"From today on, all accountants in the Ministry of Revenue must use these Western Regions numerals for bookkeeping!"

"Keep the abacus, but you must learn vertical calculation on paper!"

Li Shimin drew the cinnabar brush from the imperial desk, its tip pointing directly outside the hall.

"Ministry of War, Office of Military Equipment, Office of Agriculture!"

Several Ministers knelt down in unison.

"Three months!"

"I give you only three months to carve these ten numerals and that 'Nine-Nine Multiplication Table' onto wooden slips and distribute them to the Great Tang's prefectural and county Zhechong Fu."

"All logistics managers of the armies, treasurers of all departments, and bookkeeping clerks."

"Deadline: three months. You must memorize this formula and master this method of calculation!"

"After three months, all departments will be assessed."

"If one account is calculated wrongly, you will be dismissed from office."

"If you cannot recite the Nine-Nine formula, you will receive fifty strokes of the cane and be removed from the clerk registry!"

All civil and military officials fell silent as if frozen.

No one dared to speak out in objection.

They knew deeply that this was no child's play.

The Emperor was using violent means to forcibly replace the Great Tang's administrative efficiency with an iron-cast skeleton.

The Great Tang's mathematics and fiscal system, under the baptism of a modern children's enlightenment nursery rhyme, completed a forced evolution spanning a hundred years in a single night.

A modern apartment.

Xiao Sizi was still staring blankly at the numbers on the white paper.

She traced shapes in the air with her fingers, trying to recreate the vertical calculation Lin Xuan had just performed.

"Lin Xuan," she stopped her hand and looked at the young man leaning on the sofa. "If I master this formula, can I calculate all accounts in the world?"

She felt this skill was immense.

Once learned, she could manage accounts for the Emperor in the Imperial Treasury and never fear servants cheating again.

Hearing this, Lin Xuan let out a scoff.

He took the white paper, crumpled it into a ball, and threw it into the trash can.

"Calculate accounts? Counting change for buying snacks?" Lin Xuan looked at her, his carefree expression vanishing.

He picked up the Tablet Computer again and exited the drawing software.

"Do you truly think later generations created these numbers and invented these concise calculations just to be accountants?"