How many 7-digit telephone numbers can be compiled from the digits 0,1,2,..,8,9 that no digit is repeated?
Leave us a comment of this math problem and its solution (i.e. if it is still somewhat unclear...):
Showing 1 comment:
Solution is not correct. 0-9 is 10 digits, so n = 10 * 9 * 8 * 7 * 6 * 5 * 4 = 604800. Or, 10!/3! = 604800. If there was a restriction on the first digit, such that the first digit could not be 0 or 1, or any other number, then it would be 9. However, there is no restriction (that is given) to make this valid, so for the first digit, there are initially 10 digits to choose from. After one is taken, then it goes to 9 and etc.
To solve this verbal math problem are needed these knowledge from mathematics:
Next similar math problems:
- PIN - codes
How many five-digit PIN - code can we create using the even numbers?
Combination lock will open when the right choice of 5 numbers (from 1 to 12 inclusive) is selected. A. How many different lock combinations are possible? B. Is he combination lock named appropriately?
- Logik game
Letter game Logik is a two player game, which has the following rules: 1. The first player thinks five-letter word in which no letter is not repeated. 2. The second player writes a five-letter word. 3. The first player answers two numbers - the first numbe
- Hockey match
The hockey match ended with result 3:1. How many different storylines may have the match?
- Cars plates
How many different licence plates can country have, given that they use 3 letters followed by 3 digits?
3 children pulled 12 different toys from a box. Many ways can be divided toys so that each children had at least one toy?
- Combinations 7
A multi-course meal has 3 choices. 3 appetizers, 4 main courses, and 3 desserts. How many different combinations to choose from?
How many ways can select 4 fields on classic chess board with 64 fields, so that fields don't has the same color?
How many different ways can sit 8 boys and 3 girls in line, if girls want to sit on the edge?
- Password dalibor
Kamila wants to change the password daliborZ by a) two consonants exchanged between themselves, b) changes one little vowel to such same great vowel c) makes this two changes. How many opportunities have a choice?
How many 3 letter "words" are possible using 14 letters of the alphabet? a) n - without repetition b) m - with repetition
The table contains tennis training schedule for Saturday's younger students during the winter indoor season. Before the start of the summer season is preparing a new training schedule. Tomas Kucera will be able to practice only in the morning, sisters Kova
- 7 heroes
9 heroes galloping on 9 horses behind. How many ways can sort them behind?
- Playing cards
How many possible ways are to shuffle 7 playing cards?
- Glass with icecream
We have 6 kinds of ice cream and 5 kinds of fruit. We put 3 cups of ice cream and 2 fruits into each glass. How many can unique decorated glasses be?
- Theorem prove
We want to prove the sentence: If the natural number n is divisible by six, then n is divisible by three. From what assumption we started?
From the colors - red, blue, green, black and white, create all possible tricolors.