Form 1
Mathematics
Chapter 2
Number Patterns and Sequences
1. 自然数(natural numbers)：1, 2, 3, 4, ...
2. 偶数(Even numbers)：可被2整除（就是没有余数和小数点）
3. 奇数(Odd numbers)：不能被2整除
4. 素数(Prime numbers)：只能被2个号码除——自己和1，1不是，因为只能被1个号码除
5. 因素(factors)：能被 N 除的号码，如：N=4, factors of 4= 1, 2, 4
6. 倍数(multiples)：N 的乘法表，如：N=4, multiples of 4= 4, 8, 12, 16, 20, ...
7. LCM （lowest common multiples，最小公倍数）：找x, n 的LCM
Method a. List the multiples
if x = 3, n= 4
Multiples of 3= 3, 6, 9, 12, 15,...
Multiples of 4= 4, 8, 12, 16, ...
LCM of 3, 4 = 12
Method b. Algorithm
if x = 10, n= 12
2 )10, 12
5 ) 5, 6
6 ) 1, 6
1, 1
2*5*6= 60
60 = LCM of 10 & 12
8. HCF（highest common factor，最大公因数）：找x, n 的HCF
Method a. List all tha factors
if x=10, n=5
Factors of 10 = 1, 2, 5, 10
Factors of 5 = 1, 5
HCF of 10, 5 = 5
Method b. Algorithm
if x= 20, n=12
4)20,12
5 , 3
HCF = 4
**转载longman Super Score Mathematics Form 1，略改
Sunday, October 24
Form 1 Mathematics Chapter 2
