# What makes a number friendly?

## What makes a number friendly?

In number theory, friendly numbers are two or more natural numbers with a common abundancy index, the ratio between the sum of divisors of a number and the number itself. Two numbers with the same “abundancy” form a friendly pair; n numbers with the same “abundancy” form a friendly n-tuple.

### What is an example of a friendly number?

The numbers known to be friendly are given by 6, 12, 24, 28, 30, 40, 42, 56, 60, (OEIS A074902). Friendly numbers have a positive density.

#### What is a friendly equation?

When using an empty number line, I like to talk to the students about “friendly numbers.” A friendly number is simply a number that is easy to work with. Here’s an example of using an empty number line for the equation 18+5. First, draw a line and label the “18.” Then, it is time to find a friendly number.

What is the number strategy?

The key idea of number strategies at level 1 is that counting can be used to solve number problems. They can then solve addition and subtraction problems by counting on or back from a starting number. For example, to solve 6 + 3 they recognise that 6 represents the first set, and count on from there “… 7, 8, 9”.

What is the smallest pair of friendly number?

Amicable numbers are two different numbers related in such a way that the sum of the proper divisors of each is equal to the other number. The smallest pair of amicable numbers is (220, 284).

## What is the most beautiful number?

1.61803
What Is So Special About The Number 1.61803? The Golden Ratio (phi = φ) is often called The Most Beautiful Number In The Universe. The reason φ is so extraordinary is because it can be visualized almost everywhere, starting from geometry to the human body itself!

### Who is called number friend?

It is, in fact, an engaging story of his journey with his unique best friend called ‘numbers. ‘ Srinivasa Ramanujan played with numbers as if they were his best friends from when he was a young boy.

#### What is the 10 strategy?

In 1st grade, as students begin learning their basic addition facts, they apply that knowledge in a strategy known as “make a ten” to help make sense of facts that might otherwise be hard to memorize, such as 8 + 4 or 9 + 5. To use the strategy, students decompose one of the addends to make a ten from the other.

What is the perfect number?

Perfect number, a positive integer that is equal to the sum of its proper divisors. The smallest perfect number is 6, which is the sum of 1, 2, and 3. Other perfect numbers are 28, 496, and 8,128. The discovery of such numbers is lost in prehistory.

Are 60 and 84 amicable numbers?

Amicable Numbers The Greeks considered the pair of numbers 220 and 284 to be amicable or friendly numbers because the sum of the proper divisors of one of the numbers is the other number. a. 60 and 84 are amicable numbers.

## What is the happiest number?

Defined the happiest number as the smallest number that finds the most other happy numbers with it, i.e. 7 found four other numbers (49, 97, 130, and 10) making it a rank 4 in happiness.

### Is the number n a friendly or abundancy number?

A number n is a “friendly number” if there exists m ≠ n such that σ ( m) / m = σ ( n) / n. “Abundancy” is not the same as abundance, which is defined as σ ( n) − 2 n . equal to the sum of the k -th powers of the divisors of n . The numbers 1 through 5 are all solitary.

#### How many members are in the friendly number club?

There are clubs with more known members: in particular, those formed by multiply perfect numbers, which are numbers whose “abundancy” is an integer. As of early 2013, the club of “friendly” numbers with “abundancy” equal to 9 has 2094 known members.

What do you need to know about MSHA part 48?

This book was designed to assist mining operators and independent contractors who are regulated by MSHA’s Part 48 regulations.   It provides regulations, policy, and frequently asked questions and answers.   It also includes a blank training plan, sample lesson plans, and sample training records.

Are there any problems with the friendly numbers?

There are several unsolved problems related to the “friendly numbers”. In spite of the similarity in name, there is no specific relationship between the friendly numbers and the amicable numbers or the sociable numbers, although the definitions of the latter two also involve the divisor function.