# 9th grade (14y) + multiplication principle - examples

1. One three
We throw two dice. What is the probability that max one three falls?
2. No. of divisors
How many different divisors has number ??
3. 7 heroes
9 heroes galloping on 9 horses behind. How many ways can sort them behind?
4. Flags
How many different flags can be made from colors white, red, green, purple, orange, yellow, blue so that each flag consisted of three different colors?
5. Vans
In how many ways can 9 shuttle vans line up at the airport?
6. Seating
How many ways can 6 people sit on 3 numbered chairs (e. G. , seat reservation on the train)?
7. Guests
How many ways can 5 guests sit down on 6 seats standing in a row?
8. 2nd class variations
From how many elements you can create 2450 variations of the second class?
9. Shelf
How many ways are there to arrange 6 books on a shelf?
10. Phone numbers
How many 7-digit telephone numbers can be compiled from the digits 0,1,2,..,8,9 that no digit is repeated?
11. Rectangles
How many rectangles with area 3032 cm2 whose sides is natural numbers are?
12. Football league
In the 5th football league is 10 teams. How many ways can be filled first, second and third place?
13. Playing cards
How many possible ways are to shuffle 7 playing cards?
14. Pairs
At the table sit 8 people, 4 on one side and 4 on the other side. Among them are 3 pairs. Every pair wants to sit opposite each other. How many ways can they sit?
15. Morse alphabet
Calculate how many words of Morse code to create compiling commas and dots in the words of one to four characters.
16. Coin and die
Flip a coin and then roll a six-sided die. How many possible combinations are there?
17. Lock
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?
18. Subsets
How many are all subsets of set ??
19. Pizza
A school survey found that 12 out of 15 students like pizza. If 6 students are chosen at random, what is the probability that all 6 students like pizza?
20. Bits, bytes
Calculate how many different numbers can be encoded in 16-bit binary word?

Do you have an interesting mathematical example that you can't solve it? Enter it, and we can try to solve it.

To this e-mail address, we will reply solution; solved examples are also published here. Please enter e-mail correctly and check whether you don't have a full mailbox.