There are 10 red, yellow, blue and white balls, which are mixed and put in a cassette. At least how many balls must be found at a time to ensure that there are 6 balls in the same color

In the worst case, touch 20 balls, 5 balls of each color, so at least 21 balls should be touched to ensure 6 balls of the same color

Red, yellow, blue and white four colors of the same size of the ball each 8 mixed in a cassette, at least a touch out how many balls to ensure that there are five balls of the same color?

Red, yellow, blue and white four colors of the same size of the ball each 8 mixed in a cassette, at least a touch out how many balls to ensure that there are five balls of the same color?
Drawer problem, the key is to consider the "worst case", this problem is to touch four is the worst case
Requirement: 4 × 4 + 1 = 17
A: at least 17 balls can guarantee that 5 balls have the same color

A problem of finding regularity
For a regular number table, please go to No
Using the algebraic formula containing n (n is a positive integer one two three four)
）It represents the first line of the nth row and Nth column in the number table
The second line is 4 3 6 11
The third line 9 8 7 12
The fourth line 16 15 14 13

The number of n-th row and n-th column is
n^2-(n-1)=n^2-n+1
N ^ 2 is the square of n

Find the rules: - 2,8, - 18,32, - 50,72. What rules do they have? What's the hundredth number

n*(2n)*(-1)^n
The 100th number: 20000

Find the rule 2,8,18, (), 50, ()

2,8,18,（32 ）,50,（72 ）
law:
8-2=6
18-8=10
32-18=14
50-32=18
72-50=22
6. The difference between 10, 14, 18 and 22 was 4

The rule of 2,8,18,32,52

The square of 2 × n

5.10.17.26.37.().( )

2+3=5
5+5=10
10+7=17
17+9=26
26+11=37
37+13=50
50+15=65
Add odd numbers in turn~

Help to solve a sequence: 1,2,3,6,11,23. What's the rule?
The title is certainly no problem. The first few items and this sort of arrangement are wrong on the number of 11. It seems very easy sequence, how can not find the answer?

1+2+3=6
2+3+6=11
3+6+11=23
Each item is the sum of the first three items (starting from 6)

How to do the fun park on page 37 of class evaluation
When a salesman checked out the account, he found that the cash was 45.36 yuan less than the book. After checking the account carefully, he knew that the decimal point of a sum of money was just wrong. How much should it be?

If the decimal point of a sum of money is wrong, it should be that the cash is right. If the book is wrong, there is more money in the book
Because the decimal point is wrong by one place, the difference is ten times
If the cash is set at x yuan, it will be recorded as 10x yuan on the book
10x-x=45.36
9x=45.36
x=5.04
The calculation should be right

Fun paradise
There is a rare animal that can breed a pair of small animals every six months. After six months of growth, this pair of small animals can breed a pair of small animals. There is a cage. In the fourth year, each cell can live in one. When did this cage account for half

In the fourth year, each cell can live on one, that is, at this time there are 16 pairs of small animals, that is 32
Half of the time, that is, when there are eight pairs of small animals, that is, in the third year

There are 10 red, yellow, blue and white balls, which are mixed and put in a cassette. At least how many balls must be found at a time to ensure that there are 6 balls in the same color