Chapter 6 Principal Richardson , Director Anderson , and Linda stood in the office center like wooden posts . The principal's fat face was sagging , cold sweat soaking his shirt collar ; Director Anderson's makeup was smeared , her eyes darting around ; and Linda , who had been so arrogant before , now had a pale face and trembling lips , no longer daring to look at people sideways . When she saw us enter , especially when she saw Steven , her body shook uncontrollably . Steven's gaze didn't linger on them . He turned to the two black - suited bodyguards behind us and said , " Bring the equipment in . " The door was pushed open , and a huge , brand - new whiteboard was carried in , placed heavily in the center of the office . The three of them were startled again by this display . " Mr ... Mr. Walsh ... " The principal shuffled forward half a step , forcing out a smile that looked more like a grimace . " You see , this ... this is all a misunderstanding ! We regarding your donation ... " " Shut up , " Steven cut him off . " Right now , we're not talking about money . " He walked to the whiteboard , took a black marker pen , and placed it in my daughter's small hand . Crouching down , in a voice only the three of us could hear , he said gently , " Lily , don't be afraid . Go write it . Write down the problem that caused you such grievance . " Lily's body was still trembling slightly . She looked at me , then at the encouraging look in Steven's eyes . I held her small hand , wrapping my hand around hers , gripping the pen together . Together , we forcefully wrote two lines on the huge whiteboard : 3×5 = ? 5×3 = ? After writing , I raised my head , my gaze piercing directly at Linda . " Linda , didn't you say that 3 times 5 doesn't equal 5 times 3 ? " Linda didn't dare look at me or Steven , her eyes frantically darting around . " I ... I was talking about Chapter 6 Download 4.92 % problem - solving approaches ... logic ... " " Very good . " Steven clapped twice lightly . He stepped forward , took the pen from Lily's hand , and wrote a title on the whiteboard with flourishing strokes : " Proof of the Commutative Property of Integer Multiplication . " He threw the pen down at Linda's feet . " Aren't you the one who teaches logical rigor ? " Steven's smile grew colder . " Then please use any mathematical logic at the undergraduate level or above - group theory , ring theory , or directly use Peano axioms - to prove why the ' commutative property of integer multiplication ' holds . " The principal's fat face was twitching , Director Anderson's mouth formed an " O " shape , and Linda immediately broke out in cold sweat . " You ... you're being unreasonable ! " Linda stammered in defense . " What does this have to do with elementary Advanced Mathematics Competition ! " " Of course it's related , " I spoke coldly . " Didn't you say you don't teach grocery store arithmetic , but ' logical rigor ' ? Didn't you emphasize ' rules' the most ? " I stepped forward , staring directly into her eyes that were dodging from guilt , saying word by word , " Now , please use the you tore up gor ' and ' rules ' you're so proud of to solve this problem . When my daughter's perfect paper , weren't you very confident ? " " I ... " Linda was speechless , unable to say a word . A third - rate teacher's college graduate who had climbed to her position through scheming and bribery - she couldn't even bribery - she couldn't even understand what the problem was asking ! " Can't prove it ? " Steven laughed lightly , his laughter full of disdain . " If you can't prove something , what right did you have to tear up my daughter's perfect paper ?! " His voice suddenly rose , like thunder exploding ! Chapter 6