Posted by Lucy on Tuesday, April 9, 2013 at 10:37am.
How many numbers
from 1 to 1000
inclusive can be
expressed as the sum
of k >= 2 consecutive
positive integers for
some value of k ? Sorry to post question from Brilliant, I got 997 integers, but it's wrong. If you think you can answer ...
- Math ( Number Theory ) - Steve, Tuesday, April 9, 2013 at 11:11am
For k=2, we want all n<=1000 such that n=m+m+1 = 2m+1
That is, all odd numbers 3<=n<=999
There are 996/2+1 = 499 of those
For k=3, we want n=3m+3
so, that's all multiples of 3 with 6<=n<=999
There are 993/3+1 = 332 of those
For k=4, we want 4m+6
so, that's all multiples of 4 with 10<=n<=998
There are 988/4+1 = 248 of those
There's a pattern here, so you should be able to come up with some
expression, or just brute-force your way through.
Maybe not a lot of help, but it does show that there are more than 997 of them.
- Math ( Number Theory ) - Arpan, Wednesday, April 10, 2013 at 9:12am
The ans Steve gave is absolutely wrong...the ans is less than 823 and greater than 665...steve u have counted the same numbers more than one time...for example u have counted 15 twice....
- Math ( Number Theory ) - Anonymous, Wednesday, April 10, 2013 at 4:49pm
When I calculated out I got 990 as the correct answer.
Answer this Question
More Related Questions
- Maths - The number 1000 can be written in several ways as a sum of one or more ...
- Algebra - Joe picks 2 distinct numbers from the set of the first 14 positive ...
- Math - Most natural numbers can be expressed as a sum of two or ore consecutive ...
- Math (algebra) - Let x,y be complex numbers satisfying x+y=a xy=b, where a and b...
- math, algebra - 2a+2ab+2b I need a lot of help in this one. it says find two ...
- math plllls heelp - How many integers 1≤N≤1000 can be written both ...
- math - The sum of squares formula is given by 1^2+2^2+3^2+…+n^2=n(n+1)(2n+1)/6. ...
- SAT math - Set M consists of the consecutive integers from -15 to y, inclusive. ...
- SAT prep help - Set M consists of the consecutive integers from -15 to y, ...
- math - The sum of 5 consecutive integers is 1,000. What is the value of the ...