## Combination

According to mathematicians, the term combination refers to an arrangement in which the order of the objects does not matter. Simply stating the choosing of things or elements from one group without regard to their order is what, known as combination.

If there are several choices or subgroups that could make, the query asking how many ways a collection of objects could arrange is the combination. Or in other words, if you have to pick a group of items from a relatively bigger one in as many ways as possible, the term combination will use in that instance.

As an unordered grouping of a set’s components is called a combination.Then the several methods to arrange **r** things out of **n **things is found using the combination formula as stated below

**nCr = n!/r!(n−r)!**

Suppose you have a collection of n items.

has indicated by the letter C.

Isn’t it amazing how simple it is to solve the problem of “n C r”?

In the formula denoted above

**n **denotes the number of unique items from which you can select. Whereas the **r** is the number of objects being picked, or the number of spaces to be filled in.

Moreover, the C in the formula stands for combination, and it is not an arithmetic element. There is an exclamation sign (!) next to the number to denote its number’s factorial. Moreover combination calculators can also solve all problems related to combination.

See Combination calculator to solve faster.

## Arithmetic Sequence

A sequence of terms in which each term is equal to the sum of its predecessor and a constant has known as an arithmetic sequence. This means an arithmetic sequence is a set of integers where the difference between any two subsequent items is always the same constant value.

That constant value in an arithmetic sequence is termed as the common difference. A common difference exists between successive terms in every arithmetic sequence. You get the next term’s value by adding a common difference value to any other term in your sequence.

However, the common difference can compute by subtracting the previous value from any other value. Mathematically, for **n **larger than or equal to two, the common difference between consecutive terms in an arithmetic series, **a****n****-a****n-1**, is given as **d**.

Whereas, the **a****1** is the first value and **a****n** denotes the last term in the arithmetic sequence The arithmetic sequence is sometimes also known as arithmetic progression. The common difference could either calculated as a positive or a negative value.

Moreover, the common difference can be a whole number, a decimal number (including fractions), or an irrational number. It will always be the difference between all successive terms in that Arithmetic Sequence, regardless of its value.

This can also be solved by using an arithmetic sequence calculator.

An arithmetic sequence’s difference between subsequent components doesn’t need to be always 1 however the common difference could be any variable value.

## Rounding

‘Rounding’ refers to the process of simplifying a number while maintaining it close to its real or exact value. Although the number becomes less precise, it makes dealing with numbers and values a lot more easier.

Note that while rounding off, you evaluate whether the number is less than or higher than 5 and then round it off accordingly. The procedure of rounding off has divided into two different types including rounding up and rounding down.

### Rounding Up

The rounding up implies that no matter how little the number is, i.e. 2.1 which is less than 5, you’ll round it up to 2. Most often, this occurs when there has a financial element or money value discussed in the incident.

### Rounding Down

On the other hand, the rounding down indicates, if the value is 2.9, round it down to make it 2. So this will happen in the instances. When 4 people can ride the car out of 6. So the extra one’s need to cut from the count in order to fulfill the requirement. Also use Rounding calculator for rounding the numbers faster.

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## Probability

The probability theory is use to study random events in a logically valid manner as it provides a mathematical framework for doing so. However, the probability of an event occurring is a numerical value that indicates how probable it is that the event will occur.

This number is always in the range of 0 to 1, with 0 indicating impossibility and 1 indicating certainty in the situation. A fair coin toss is a typical example of a probability experiment, in which the two potential outcomes are either heads or tails, and the outcome will determine by chance.

In this situation, there is a 50 percent chance of having either a head or a tail. However, in a sequence of coin flips, we may obtain more or less than 50 percent heads, depending on the circumstances. In the long term, however, the frequency of heads will inevitably grow as the number of flips increases, and eventually reach 50 percent.

Thus the likelihood of an event occurring let’s suppose A is the number of ways in which A may occur divided by the total number of other possibilities (number of all other possibilities).As a result, we may refer to this as the “counting definition of probability,” mostly because each conceivable event to count is frequent and discrete, which allows us to simplify the concept of probability even more. However, it is still beneficial to study the underlying rules in this case.

## Expected Value

The expected value as in probability theory is a theoretical value that indicates the average return that would obtained. If the activity were performing indefinitely.

To calculate the expected value the weighted average of all potential outcome values has calculated. Whereby the probability of the provided results will follow as the weight.

Expected value can be calculated in the same way using the formula in which the results of the event is denoted using the **x** whereas the probability of the occurring event is represented as **P(x)**

**E(x) = x**1** * P(x**1**) + x**2** * P(x**2**) + x**3** * P(x**3**)…**

In the equation above we can include as many **x****z**** * P(x****z****)** as we want, since there are possible outcomes for the action we are calculating or in other words which is the maximum number conceivable.

Moreover, for the expected value formula, there is also a shorter way to express and calculate as

**E(x) = ****Σ****x * P (x)**

It should noted that the formula comprising the sigma depicts the same thing as mentioned in the summation explanation. The sigma or summation represents the weighted mean of the potential outcomes. Wherein the probability of each event taking place in the event will represent as the weight.