## 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!)