Numbers: Chapter Summary
6th Maths : Term 2 Unit 1
Amicable Numbers
Two numbers are said to be amicable numbers if the sum of the factors of one number (except the number itself) gives the other number.
The numbers 220 and 284 are amicable, since the sum of the factors of 220 (except 220) i.e., 1 + 2 + 4 + 5 + 10 + 11 + 20 + 22 + 44 + 55 + 110 = 284 and the sum of the factors of (except 284) i.e., 1 + 2 + 4 + 71 + 142 = 220.
Check whether 1184 and 1210 are amicable numbers.
Summary
A natural number greater than 1, having only two factors namely 1 and the number itself, is called a prime number.
A natural number having more than two factors is called a composite number.
A pair of prime numbers whose difference is 2 is called as twin primes.
Every composite number can be expressed as a product of prime numbers in a unique way.
The Highest Common Factor of any two non-zero whole numbers is the largest common factor of both the numbers.
The Least Common Multiple of any two non-zero whole numbers is the smallest common multiple of both the numbers.
Two numbers having 1 as their only common factor are said to be co-primes or relatively prime.
The product of two given numbers is equal to the product of their HCF and LCM.