Mental Maths Lesson 2

Divisible rules continues


divisible by 6 --> it must be comply with rule of 2 and 3.
When adding all digit numbers and if that number is divisible by 3 and original number is even number, then original number is divisible by 6.

Eg) 12342 (sum of all digits is 12, 12 is divisible by 3, and 12342 is even number therefore 12342 is divisible by 6)

15698502(sum of all digits is 36, 36 is divisible by 3, and 15698502 is even number therefore 15698502 is divisible by 6)

6573(sum of all digits is 21, 21 is divisible by 3 however 6573 is NOT even number therefore 6573 is NOT divisible by 6)



divisible by 7 --> double the last digit, subtracting from the remaining number and get 0 or a multiple of 7, then the original number is divisible by 7.

Eg) 637
Double 7, which is 14. Subtract 14 from 63 is equal to 49.
Since 49 is multiple of 7, 637 is divisible by 7.

210
Double 0, which is 9. Subtract 0 from 21 is equal to 21.
Since 21 is multiple of 7, 210 is divisible by 7.

602
Double 2, which is 4. Subtract 4 from 60 is equal to 56.
Since 56 is multiple of 7, 602 is divisible by 7.


Divisible by 8 --> 8 * 125 = 1000, therefore any multiples of 1000 is divisible by 8. Therefore we need to look at last 3 digits and if that number is divisible by 8 then original number is divisible by 8.

Eg) 1234580 (this number is 1234000 + 580, since 1234000 is multiple of 1000, we just need to see if 580 is divisible by 8 or not, and 580 is NOT divisible by 8 therefore 1234580 is NOT divisible by 8)

7499912 (this number is 7499000 + 912, since 7499000 is multiple of 1000, we just need to see if 912 is divisible by 8 or not, and 912 is divisible by 8 therefore 7499912 is divisible by 8)

7496 (this number is 7000 + 496, since 7000 is multiple of 1000, we just need to see if 496 is divisible by 8 or not, and 496 is divisible by 8 therefore 7496 is divisible by 8)


divisible by 9 --> When adding all digit numbers and if that number is divisible by 9 then original number is divisible by 9.

Eg) 12342 (sum of all digits is 12, 12 is NOT divisible by 9 therefore 12342 is NOT divisible by 9)

15698502(sum of all digits is 36, 36 is divisible by 9 therefore 15698502 is divisible by 9)

8748(sum of all digits is 27, 27 is divisible by 9 therefore 8748 is divisible by 9)


That's it for lesson 2. I will come back with Lesson 3 soon.



[수학] 7학년 C등급에서 11학년 A등급까지 - 결과로 증명하는 24년 경력 과외
안녕하세요, 2002년부터 호주에서 수많은 학생의 수학을 책임져온 전문 튜터입니다. 단순히 문제 풀이 기술만 가르치는 것이 아니라, 수학적 사고력을 길러 성적이 자연스럽게 따라오는 수업을 지향합니다.

✅ 이런 성과를 만들어냈습니다

성적 수직 상승: 7학년 당시 C등급이었던 학생을 지도하여, 12학년 현재까지 수학 전 과목 A등급 및 우등반(Honours) 유지

고학년 만점 배출: 최근 Mathematical Methods(MM) 및 Specialist Mathematics(SM) 시험 만점자 배출

장기 지도 노하우: 20년 이상의 티칭 경험으로 다져진 독보적인 암산법과 쉬운 개념 설명

✅ 수업 방식 및 특징

99.5% 영어 수업 가능: 현지 학교 커리큘럼에 최적화된 영어 설명

근본적인 실력 향상: 단기 주입식이 아닌, 수학에 재미를 느끼고 스스로 사고하는 습관 형성

대상: 기초를 탄탄히 다지고 싶은 학생부터 Maths Methods / Specialist Maths 고득점을 노리는 학생까지 (year4 to year12)

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