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Re: Check if this basic Python script is coded right

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On 10/26/2013 2:20 PM, MRAB wrote:
> On 26/10/2013 18:36, HC wrote:
>> I'm doing my first year in university and I need help with this basic
>> assignment.
>>
>> Assignment: Write Python script that prints sum of cubes of numbers
>> between 0-200 that are multiples of 3. 3^3+6^3+9^3+12^3....+198^3=?
>>
>> My script:
>> count = 0
>> answer = 0
>>
>> while count<200:
>>      if count%3==0:
>>          answer = answer + count**3
>>      count = count + 1
>>
>> print ("Result is: " +str(answer))
>>
>> Is it all okay?
>>
> Just one small point: the assignment says that the numbers should be in
> the range 0-200, but the loop's condition is count<200 it's excluding
> 200, so the numbers will actually be in the range 0-199.

'Between 0-200' could well be interpreted to exclude both 0 and 200 and 
to mean 'in 1-190'. Problem posers should be clear about ranges and 
students should be careful to understand the problem given.

> However, as 200 isn't a multiple of 3, it won't affect the result, but
> in another assignment it might.
>
> (For the record, this is known as an "off-by-one" error.)

Unfortunately common.

-- 
Terry Jan Reedy

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Thread

Check if this basic Python script is coded right HC <hikmat@jafarli.net> - 2013-10-26 10:36 -0700
  Re: Check if this basic Python script is coded right Joel Goldstick <joel.goldstick@gmail.com> - 2013-10-26 13:53 -0400
  Re: Check if this basic Python script is coded right Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-10-26 18:55 +0100
  Re: Check if this basic Python script is coded right John Ladasky <john_ladasky@sbcglobal.net> - 2013-10-26 10:58 -0700
  Re: Check if this basic Python script is coded right MRAB <python@mrabarnett.plus.com> - 2013-10-26 19:20 +0100
    Re: Check if this basic Python script is coded right rusi <rustompmody@gmail.com> - 2013-10-27 05:20 -0700
      Re: Check if this basic Python script is coded right Tim Delaney <timothy.c.delaney@gmail.com> - 2013-10-28 08:30 +1100
  Re: Check if this basic Python script is coded right Terry Reedy <tjreedy@udel.edu> - 2013-10-26 15:46 -0400
  Re: Check if this basic Python script is coded right Terry Reedy <tjreedy@udel.edu> - 2013-10-26 16:16 -0400

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