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# Arithmatics

For the Rankers

Factors and multiples

If a number ‘a’ divides another number’ b’ exactly we say that a is a factor of b in other case b is called multiple of a

or

Factors and multiples:    If a number is exactly divisible by another number without leaving any reminder, then the second number is called to be a factor of first number

In other words, an exact divisor of number is called a factor of number

1. One is a factor of every number

2. Every number is a factor of itself

3. A number is exactly divisible by its factors

4. Factors of a number are less than or equal to that number

5. Number of factors of numbers are finite

Common factors:  Factors that two numbers have in common are called common factors of those numbers

Multiples: A multiple of number is a number obtained by multiplying it with other numbers

In other words, the product of two or more numbers is said to be multiple of each of those numbers 1. Multiples of number is greater than or equal to that number

2. Every number is a multiple of itself

3. Every multiple of number is exactly divisible by other number

4. Number of multiples of number are infinite

Common multiples:

A common multiple is a number that is a multiple of two or more numbers

Prime numbers:

The numbers which you have only two factors are called prime numbers that are 1 and itself

for example 2: 2 is having only two factors 1, 2 as factors

1. 1 is a factor of every number and every number is a factor of itself

2. So, the prime number will have two factors there are 25 prime numbers between 1 and 100.

FACTS:

1. Two is a even prime number and the first prime number

2. 3 is a first odd prime number

3. 4 is first composite number

4. 1 is neither prime nor composite

5. There is no other even prime accept 2.

6. The two numbers which are prime and having difference 2 are called twin primes.

Examples (3, 5),  (5, 7), ( 11, 13), ( 17, 19) and so on…

Bits on Factors and multiples

1. Number of prime numbers between 20 to 50 are _________

a) 6                    b) 7             c) 8              d) none

2. Number of factors of 50 are _____

a) 6                    b) 7             c) 8              d) none

3. The numbers x, x+2, x+4 are prime, then value of x is

a) 3                     b) 2            c) 11              d)17

4. Sum of all the factors of 6 is

a) 6                    b) 12            c)36             d) none

5. The numbers x, x-2 and x-6 are all prime numbers, so find the value of x

a)15                    b) 17             c) 19              d)21

6. The sum of first five multiples of 6 is ___

a)90                   b)54             c) 30              d) 84

7. The total number of the factors of 24 is ____

a)8                     b) 7              c) 4                 d) 9

8. Which of the following is not  a factors of 105 are___

a) 1                     b) 8              c) 79               d)158

9. The number of multiples of 3 which are less than 25?

a) 6                    b) 7               c) 8                  d) 9

10. The sum of first 7 multi[es of 13 is approximately

a) 360               b) 365           c)370              d)375

Solution are available with explanation in video watch  channel TNR ED https://www.youtube.com/channel/UCbCMuMDhwIdtFjQH8GGxH6A

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