81 is an odd number between 7 and 350 that has 3 factors other than itself and 1.
The numbers for which the sum of its proper factors is 1 less than the number is the powers of 2; less than 50 these are: 2, 4, 8, 16 & 32.
Numbers can be checked to see if they are primes simply by factoring them. Every prime number has exactly two factors, 1 and the number itself. If there are more or less than 2 factors, the number is not a prime. 1 has only one factor so it is not a prime, and composite numbers have 3 or more factors.
Every prime number has exactly two factors. They are '1' and the number itself. There are 15 prime numbers less than 50. A few of them are 2, 3, 5, 7, 11, 13, and 47.
Use the definition of a perfect number! Add the factors; if the sum of all the factors (excluding the number itself) is equal to the number, it is a perfect number, otherwise it isn't. (Actually, the only perfect numbers less than 100 are 6, and 28.)Use the definition of a perfect number! Add the factors; if the sum of all the factors (excluding the number itself) is equal to the number, it is a perfect number, otherwise it isn't. (Actually, the only perfect numbers less than 100 are 6, and 28.)Use the definition of a perfect number! Add the factors; if the sum of all the factors (excluding the number itself) is equal to the number, it is a perfect number, otherwise it isn't. (Actually, the only perfect numbers less than 100 are 6, and 28.)Use the definition of a perfect number! Add the factors; if the sum of all the factors (excluding the number itself) is equal to the number, it is a perfect number, otherwise it isn't. (Actually, the only perfect numbers less than 100 are 6, and 28.)
Prime numbers
The numbers for which the sum of its proper factors is 1 less than the number is the powers of 2; less than 50 these are: 2, 4, 8, 16 & 32.
A number is prime if its only two factors are one and itself.
Numbers can be checked to see if they are primes simply by factoring them. Every prime number has exactly two factors, 1 and the number itself. If there are more or less than 2 factors, the number is not a prime. 1 has only one factor so it is not a prime, and composite numbers have 3 or more factors.
Every prime number has exactly two factors. They are '1' and the number itself. There are 15 prime numbers less than 50. A few of them are 2, 3, 5, 7, 11, 13, and 47.
1 is the number less than fifty with the fewest number of factors. All other numbers have at least two factors (1, and the integer itself).
Composite numbers can be written that way.
Use the definition of a perfect number! Add the factors; if the sum of all the factors (excluding the number itself) is equal to the number, it is a perfect number, otherwise it isn't. (Actually, the only perfect numbers less than 100 are 6, and 28.)Use the definition of a perfect number! Add the factors; if the sum of all the factors (excluding the number itself) is equal to the number, it is a perfect number, otherwise it isn't. (Actually, the only perfect numbers less than 100 are 6, and 28.)Use the definition of a perfect number! Add the factors; if the sum of all the factors (excluding the number itself) is equal to the number, it is a perfect number, otherwise it isn't. (Actually, the only perfect numbers less than 100 are 6, and 28.)Use the definition of a perfect number! Add the factors; if the sum of all the factors (excluding the number itself) is equal to the number, it is a perfect number, otherwise it isn't. (Actually, the only perfect numbers less than 100 are 6, and 28.)
Prime numbers
Abundant, deficient and perfect numbers are determined by the sum of the proper divisors (or factors) of a number, which excludes the number itself. The factors of 76 are : 1,2,4,19,38,76 . . . after excluding the number itself the sum of the proper divisors is :- 1+2+4+19+38= 64 Deficient numbers occur when the sum of the proper divisors is less than the number itself. As 64 is less that 76 then it is deficient.
You test them, one at a time, to weed out any that has factors besides ' 1 ' and itself. When you do that, you find that 2, 3, 5, 7, 11, and 13 are prime numbers.
If the two numbers have no common factors other than 1, the LCM will be their product. If there are other common factors, the LCM will be less.
They all are prime numbers except 1