# What is a near perfect number?

In mathematics, an

**almost perfect number**(sometimes also called slightly defective or least deficient**number**) is a natural**number**n such that the sum of all divisors of n (the sum-of-divisors function σ(n)) is equal to 2n − 1, the sum of all proper divisors of n, s(n) = σ(n) − n, then being equal to n − 1.A.

### What are the first 5 perfect numbers?

List of perfect numbers

Rank | p | Perfect number |
---|---|---|

2 | 3 | 28 |

3 | 5 | 496 |

4 | 7 | 8128 |

5 | 13 | 33550336 |

#### What is a group of twelve called?

The usual ordinal form is "twelfth" but "dozenth" or "duodecimal" (from the Latin word) is also used in some contexts, particularly base-12 numeration. Similarly, a**group of twelve**things is usually a "dozen" but may also be referred to as a "duodecad".#### Is a zero a perfect square or not?

**Zero**has one**square**root which is 0. Negative numbers don't have real**square**roots since a**square**is either positive or 0. The**square**roots of numbers that are not a**perfect square**are members of the irrational numbers. This means that they can't be written as the quotient of two integers.#### Is the number 1 a perfect square?

In mathematics, a**square**number or**perfect square**is an integer that is the**square**of an integer; in other words, it is the product of some integer with itself. For example, √9 = 3, so 9 is a**square**number. A positive integer that has no**perfect square**divisors except**1**is called**square**-free.

B.

### How do you figure out what a perfect number is?

A

**number**is**perfect**if the sum of its proper factors is equal to the**number**. To find the proper factors of a**number**, write down all**numbers**that divide the**number**with the exception of the**number**itself. If the sum of the factors is equal to 18, then 18 is a**perfect number**. The first 10**perfect numbers**are shown below.#### What is meant by amicable numbers?

**Amicable numbers**are two different**numbers**so related that the sum of the proper divisors of each is equal to the other**number**. (A proper divisor of a**number**is a positive factor of that**number**other than the**number**itself. For example, the proper divisors of 6 are 1, 2, and 3.)#### What are the first 5 perfect numbers?

List of perfect numbersRank p Perfect number 2 3 28 3 5 496 4 7 8128 5 13 33550336 #### How many perfect numbers are there?

A perfect number is defined to be one which is equal to the sum of its aliquot parts. The**four perfect numbers**6, 28, 496 and**8128**seem to have been known from ancient times and there is no record of these discoveries.

C.

### How many perfect numbers are there?

A perfect number is defined to be one which is equal to the sum of its aliquot parts. The

**four perfect numbers**6, 28, 496 and**8128**seem to have been known from ancient times and there is no record of these discoveries.#### Can there be an odd perfect number?

**Perfect numbers**are positive integers that are the sum of their proper divisors. For instance, 6 is a**perfect number**, because the sum of its proper divisors, 1, 2, and 3 equals 6 (1 + 2 + 3 = 6). Furthermore, in the letter, Descartes was the first to reason that an**odd perfect number**may or may not exist.#### Are there an infinite number of Mersenne primes?

If is also a**prime**, then it is known as a**Mersenne Prime**. It is well known from Euclid's proof that**there**exist**infinitely**many regular**primes**. However, for some special sets of**prime**numbers (**Mersenne Primes**, Sophie-Germain**Primes**, Twin**Primes**, etc.) this question has never been answered.#### What is a strong number?

**Strong number**:**Strong numbers**are the**numbers**whose sum of factorial of digits is equal to the original**number**. Example: 145 is a**strong number**. Since 1!

Updated: 3rd September 2018