# What is the formula for combinations with repetition?

## What is the formula for combinations with repetition?

If we are selecting an r-combination from n elements with repetition, there are C(n+r-1,r)=C(n+r-1,n-1) ways to do so.

Does order matter with combinations?

Permutations are for lists (order matters) and combinations are for groups (order doesn’t matter). You know, a “combination lock” should really be called a “permutation lock”. The order you put the numbers in matters.

### What are arrangements with repetition?

Item arrangements with repetition (also called k-permutations with repetition) are the list of all possible arrangements of elements (each can be repeated) in any order.

Why does order not matter in combinations?

It doesn’t matter in what order we add our ingredients but if we have a combination to our padlock that is 4-5-6 then the order is extremely important. If the order doesn’t matter then we have a combination, if the order do matter then we have a permutation. One could say that a permutation is an ordered combination.

## Does it matter in what order you select the objects?

A permutation is an arrangement of items in a particular order. A combination is a collection of items chosen from a set, where the order of selection doesn’t matter.

How many possibilities are there with 4 options?

If you meant to say “permutations”, then you are probably asking the question “how many different ways can I arrange the order of four numbers?” The answer to this question (which you got right) is 24.

### How many combinations of the numbers 1 2 3 4 are there?

Explanation: If we are looking at the number of numbers we can create using the numbers 1, 2, 3, and 4, we can calculate that the following way: for each digit (thousands, hundreds, tens, ones), we have 4 choices of numbers. And so we can create 4×4×4×4=44=256 numbers.

How many numbers can be formed with the digits 1 2 3 4 3 2 1 so that the odd digits always occupy the odd places?

` Hence, the required number of numbers `=(6xx3)= 18.

## How many different numbers can be formed with digits 1 3 5 7 9 when take all at a time and what is their sum?

= 24 such numbers.

How many 3 digit numbers can be formed using the digits 2 3 4 and 5 as often as desired?

I was able to get this question, by changing 2, 3, 4 and 5 to 1, 2, 3 and 4; then multiplying 4 by 3 by 2 to give 24 possibilities.

### How many three digits numbers can be formed using the digits 1,2 3 4 5 if digits Cannot be repeated?

There are 504 different 3-digit numbers which can be formed from numbers 1, 2, 3, 4, 5, 6, 7, 8, and 9 if no repetition is allowed. Calculate 5!

Does order matter without replacement?

Permutations and Combinations: n P r , n C r . Choosing without replacement, order matters, order does not matter.

## Does order matter math?

From your earliest days of math you learned that the order in which you add two numbers doesn’t matter: 3+5 and 5+3 give the same result.

What are some combinations with repetition?

Combinations with Repetition 1 {c, c, c} (3 scoops of chocolate) 2 {b, l, v} (one each of banana, lemon and vanilla) 3 {b, v, v} (one of banana, two of vanilla) More

### What are the different types of combinations?

There are also two types of combinations (remember the order does not matter now): 1. Combinations with Repetition Actually, these are the hardest to explain, so we will come back to this later. 2. Combinations without Repetition

What is a combination of numbers without repetition?

Combinations without Repetition. This is how lotteries work. The numbers are drawn one at a time, and if we have the lucky numbers (no matter what order) we win! The easiest way to explain it is to: assume that the order does matter (ie permutations), then alter it so the order does not matter.

## How many ways can 1 2 3 be placed in order?

In fact there is an easy way to work out how many ways “1 2 3” could be placed in order, and we have already talked about it. The answer is: (Another example: 4 things can be placed in 4! = 4 × 3 × 2 × 1 = 24 different ways, try it for yourself!)