UNIT 2 DIVISIBILITYUNIT 2 DIVISIBILITY

Manuel Jiménez Martínez 1ºA

INDEX- Divisibility

- Multiples and factors

- Prime number

- Composite number

- Rules of divisibility

- H.C.F.

-L.C.M.

WHEN IS A NUMBER DIVISIBLE BY ANOTHER NUMBER?

When the division is exact.

EXAMPLE:EXAMPLE: 18 : 2 = 9

Eighteen is divisible by nine and two.

When is a number multiple or factor When is a number multiple or factor of another number? of another number?

When the division is exact

EXAMPLE: EXAMPLE: 28 : 4 = 728 : 4 = 7

Twenty-eight is multiple of fourTwenty-eight is multiple of four

Four is factor of twenty-eightFour is factor of twenty-eight

What are prime numbers?

Are numbers with only two divisors, 1 and itselfAre numbers with only two divisors, 1 and itself

EXAMPLE:EXAMPLE: The prime numbers are 2,3,5,7,11,The prime numbers are 2,3,5,7,11,

13,17,19,23,29,31,37,41,43,47,53,59,61,67,13,17,19,23,29,31,37,41,43,47,53,59,61,67,

71,73,79,83,89 and 97.71,73,79,83,89 and 97.

What are composite numbers?

Are numbers with more than two divisors

EXAMPLE: EXAMPLE: 10 = 1,2,5 and 1010 = 1,2,5 and 10

RULES OF RULES OF DIVISIBILITYDIVISIBILITY

H.C.F. AND L.C.MH.C.F. AND L.C.M● EXAMPLE:EXAMPLE:● H.C.F(18 and 9)= H.C.F(18 and 9)=

2·3·3= 2·3·3= 1818● 18=2·3·318=2·3·3● 9=3·39=3·3

● EXAMPLE:EXAMPLE:● L.C.M(10 and 5)=L.C.M(10 and 5)=● 2·5= 2·5= 1010● 10= 2·510= 2·5● 5= 55= 5

TTHHE E EENNDD