If a garage door opener has a 10-digit keypad and the code to open the door is a 4-digit code,how many codes are possible?
686

Question

anonymous · Answer

686 is the answer??

anonymous · Answer

10P4

anonymous · Answer

i think 5040 is the answer..is it coorectt??

anonymous · Answer

5040 must be the answer

anonymous · Answer

I'm sorry but what are you people thinking:
0-9999 or 10^4 should be the correct answer

anonymous · Answer

no way 
10P4=5040

anonymous · Answer

You don't have a fixed set of objects you arrange in a permutation
because you can reuse the digits

anonymous · Answer

we'r reusin the digitis that's why evrytime its a differnt arrangement!...so it's permutation!

myininaya · Answer

_ _ _ _
 each of the 4 numbers can be 0,1,2,3,4,5,6,7,8, or 9
thats 10 different ways we can choose each of the 4

anonymous · Answer

i m choosing 4 then arranging them it is what 10 P4 stands for

myininaya · Answer

so it would be 10*10*10*10

myininaya · Answer

or 10^4

anonymous · Answer

myininaya I don't think they understand what a permutation is

anonymous · Answer

look i choose 4 then tried possible arrangements of them......and u people are using basic counting principle

anonymous · Answer

Hashir, you can use each digit more than once in each code

anonymous · Answer

You aren't applying a permutation on a set of objects, since you can repeat those objects in the code as many times as you like.

myininaya · Answer

ok what about if we had a two digit code
we can only choose each of the digits to be 0,1,2,3,4
thats 5 ways we can choose each
so 5*5=25

possible codes:
00
01
02
03
04
10
11
12
13
14
20
21
22
23
24
30
31
32
33
34
40
41
42
43
44

how many codes is that

anonymous · Answer

i think i got it.....

myininaya · Answer

25 codes and that would be the way me and alchemista would have found it by doing 5*5

anonymous · Answer

10^4 is right ......what was i thinking

anonymous · Answer

thnx guys

salina · Answer

what ia answer?

anonymous · Answer

10^4=10000

myininaya · Answer

and i'm not writing all the possible codes for this problem lol

anonymous · Answer

It would just be listing the numbers from 0-9999 but padding it with zeros

myininaya · Answer

lol
no thanks

salina · Answer

10000 way or 
10!/(10-4)!

anonymous · Answer

I can write some python to do it, heheheh

myininaya · Answer

lol
10^4 is the answer 
or 10000

salina · Answer

ty

anonymous · Answer

damn..i am a neophyte..thnx guys!!