Number 3 Appearing 1-1000: Counting Stats

  • Thread starter Thread starter Abderrahim
  • Start date Start date
  • Tags Tags
    Statistic
Abderrahim
Messages
1
Reaction score
0
How many times will the number 3 appear in counting numbers from 1 to 1000?

PS: Just joined the forums.
 
Physics news on Phys.org
Hi there,

I'm not sure if it's really statistics, and it sounds a bit like a homework question...

Here's a hint:
there's 1 3 in the units digit in every nnn0..nnn9
there's 10 3s in the tens digit in ever nn00..nn99
etc...

Mathematica can construct all of the digits and count the number of 3s using
Count[Flatten[IntegerDigits/@Range[1000]], 3]
 

Thread '##(A/\mathfrak{a})_{\mathfrak{p}/\mathfrak{a}}## and its isomorphism?'

I asked online questions about Proposition 2.1.1: The answer I got is the following: I have some questions about the answer I got. When the person answering says: ##1.## Is the map ##\mathfrak{q}\mapsto \mathfrak{q} A _\mathfrak{p}## from ##A\setminus \mathfrak{p}\to A_\mathfrak{p}##? But I don't understand what the author meant for the rest of the sentence in mathematical notation: ##2.## In the next statement where the author says: How is ##A\to...
View full post »

Thread 'Trouble understanding an online solution to an exercise in Dummit & Foote'

##\textbf{Exercise 10}:## I came across the following solution online: Questions: 1. When the author states in "that ring (not sure if he is referring to ##R## or ##R/\mathfrak{p}##, but I am guessing the later) ##x_n x_{n+1}=0## for all odd $n$ and ##x_{n+1}## is invertible, so that ##x_n=0##" 2. How does ##x_nx_{n+1}=0## implies that ##x_{n+1}## is invertible and ##x_n=0##. I mean if the quotient ring ##R/\mathfrak{p}## is an integral domain, and ##x_{n+1}## is invertible then...
View full post »

Thread 'Questions about non existence of GCDs vs (coimages, cokernels)'

The following are taken from the two sources, 1) from this online page and the book An Introduction to Module Theory by: Ibrahim Assem, Flavio U. Coelho. In the Abelian Categories chapter in the module theory text on page 157, right after presenting IV.2.21 Definition, the authors states "Image and coimage may or may not exist, but if they do, then they are unique up to isomorphism (because so are kernels and cokernels). Also in the reference url page above, the authors present two...
View full post »

Similar threads

Counting letters in a number between 1 and 1000
Replies
10
Views
1K
How do you count unique elements when multiplying integers from 1 to 1000?
Replies
18
Views
4K
Question about counting rate in a detector
Replies
1
Views
2K
I Need help understanding base-10 number format please
Replies
2
Views
1K
I Proving inequality about dimension of quotient vector spaces
Replies
25
Views
3K
Conditional expectations related to count of event occurring kth time
Replies
2
Views
1K
A Confused about magnitude of error
Replies
18
Views
3K
Python Trying to determine the number of coin tosses for HHTH
Replies
10
Views
2K
MHB Solve Integer & Inequality: $x=(x-1)^3$ for $N$
Replies
1
Views
1K
Leakage of Air in a Spacecraft
Replies
16
Views
1K

Hot Threads

Recent Insights

Back
Top