3.1.1 ICT Check Digit
- Created by: Bellaxox
- Created on: 06-11-17 08:42
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- ICT AS 3.1.1
- Check Digit
- Modulus 11 check digit
- When using this the last digit is always 2
- The first digit is the length of the digits add 1 e.g. length is 5 so its 5 + 1 = 6 therefore 6 is the first digit
- The middle digit go down in scale e.g. 5,4,3,2 these are the numbers between the first and last digit
- You then multiple the digit by the weight
- You then add all the multiples together
- You then divide this by 11
- Divide the remainder e.g. 6.7 by 11
- Example
- 9317
- Length of digit is 4
- Last digit is 2
- First digit is 4 + 1 = 5
- Middle digits (weight) are 5,4,3,2
- Digit = 9137
- Weight = 5432
- Multiple = 9*5 = 45, 1*4 = 4, 3*3 = 9, 7*2 = 14
- 45 + 4 + 9 + 14 = 72
- 72 / 11 = 6.6
- 11 - 6 = 5
- Check digit = 93175
- 11 - 6 = 5
- 72 / 11 = 6.6
- 45 + 4 + 9 + 14 = 72
- Multiple = 9*5 = 45, 1*4 = 4, 3*3 = 9, 7*2 = 14
- Weight = 5432
- 9317
- Check digit
- Is an extra digit added to the end of a data number
- An extra digit is the result of a calculation
- The calculation is peformed on the original data
- The check digit that is entered is compared with the check digit the computer calculates
- How to:
- 1. Add the odd number positioned digits together e.g. 1,3,5
- Example
- 98377102 9+3+7+0 = 19
- 19 * 3 = 57
- 8+7+1+2 = 18
- 57 + 18 = 75
- 75 / 10 = 7.5
- 10 - 5 = 5
- Check digit 983771025
- 10 - 5 = 5
- 75 / 10 = 7.5
- 57 + 18 = 75
- 8+7+1+2 = 18
- 19 * 3 = 57
- 70970156 7+9+0+5 = 21
- 21 * 3 = 63
- 0+7+1+6 = 14
- 63 + 14 = 77
- 77 / 10 = 7.7
- 10 - 7 = 3
- 709701563
- 10 - 7 = 3
- 77 / 10 = 7.7
- 63 + 14 = 77
- 0+7+1+6 = 14
- 21 * 3 = 63
- 98377102 9+3+7+0 = 19
- ISBN Check Digit
- ISBN are 10 characters long
- It is 9 digits + the check data
- The weight is 10 as it is 9 + 1
- it descends down in order
- Example
- ISBN = 0-201-67281
- First digit = 10 (9+1)
- Last digit = 2
- 0*10 = 0, 2+9 = 18, 0*8= 0, 1*7 = 7, 6*6 = 36, 7*5 = 40, 2*4 = 8, 8*3 = 24, 1*2 = 2
- 0 + 18 + 0 + 7 + 36 + 40 + 8 + 24 + 2 = 135
- 135 / 11 = 12.3
- 11 - 3 = 8
- ISBN = 0-201-672818
- 11 - 3 = 8
- 135 / 11 = 12.3
- 0 + 18 + 0 + 7 + 36 + 40 + 8 + 24 + 2 = 135
- ISBN = 0-201-67281
- 1. Find the weight (length of number add 1)
- 2. Multiple the digit by weight
- 3. Add the numbers from 2 together
- 4. Divide the result of 3 by 11
- 5. Identify the remainder of the result from 4
- 6. Subtract the remainder from 11 to get the check digit
- 5. Identify the remainder of the result from 4
- 4. Divide the result of 3 by 11
- 3. Add the numbers from 2 together
- 2. Multiple the digit by weight
- The highest weight is calculated by adding 1 to the length of the number
- Modulus 11 check digit
- Types of data
- Direct
- Gathered from an original source
- Indirect
- Gathered from another source or as a by product of another operation
- Sources of data
- Direct data source is it used for the same purpose for what it has been collected.
- Advantage
- The data that is collected is the data needed
- The original source data can be trusted
- Dis-advantages
- Can be costly to collect original data (e.g. phone calls)
- It can take time to collect the data and may not be ready in time
- If statistical data is required then it may not be possible to get a large enough sample of data
- Advantage
- Indirect data is the data is used not for the same purpose it was collected for, the data is used for a different reason it was collected for.
- Advantages
- There is no need to wait for the data to be collected as its already available
- Various difference sources of data can be used and compared to verify the accuracy of the data
- More likely to be a large sample of data is statistical analysis is required
- Dis-advantages
- The data may not meet all of the needs of the new purpose of use
- The data maybe out of date if it was collected a long time ago
- The source may not be trustworthy as collecting it directly because it was collected a different time for a different purpose
- Only summary information maybe available rather then the detail required
- The original data maybe biased. For example names and addresses from a football club maybe male dominated
- The data maybe presented in a format that makes it difficult to extract the information required
- Advantages
- Direct data source is it used for the same purpose for what it has been collected.
- Static
- Data can not be changed, i.e. a book, dvd
- Advantages
- No risk of virus
- No need for internet connection
- Can be reliable as they have been produced for a reason
- Information likely to be more relevant
- Dis-advantages
- Limited info
- Books and CD's take long time to produce
- Books and Cds can be damanged
- Only one person can use them at a time
- Dynamic
- This is data that can be changed i.e. electronically stored data like a news article online
- Advantages
- More likely to be up ti date
- Hyperlinks can be used to visit relative sites or info
- Many users can visit the website at a time
- Wide range of results therefore a good chance of finding what you need
- Disadvantage
- Not always accurate
- Location of pages can change
- Malware damage
- Internet access needed
- Wide range of unneeded results
- Quality of data
- Gigo (Garbage in, garbage out)
- If data input is poor the resulting information output will be poor
- Example: If register is filled in wrong it will have the wrong output
- Six Facts to make Gigo
- Age, how old/ up to date it is
- Accuracy, need to be accurate to be reliable
- Completeness, only having part of information is worthless
- Relevance, it must be relevant
- Presentation, must be presentable
- Level of detail, given either too much or too little
- Gigo (Garbage in, garbage out)
- Direct
- Encoding data
- Replacing data with shorter data
- E.g. January - Jan, February - Feb
- It is not encryption where it is scrambled until you unlock it
- Reasons for encoding
- Less chance of spelling or incorrect data input
- Reduce the amount of storage needed
- Improve presentation
- Secure
- Speeds up processing time
- Numerical data
- Assigning numbers to data
- E.g. 1 being science, 3 being phone, 11 being Jade
- Dis-advantages
- System can make no sence
- Not always clear on the number e.g. 2077 could be 2,0,77
- Assigning numbers to data
- Abbreviation
- Uses a shortened version of the data
- Uses letters from original text
- E.g. SCI - science, ENG - English,
- Dis-advantage
- Shorting it to three letters work for certain things but not all e.g. Art
- Value judgement
- Usually used in questionnaires
- E.g. Rate the quality from 1 to 10
- Advantages to encoding
- Less data to store
- Speed of processing, smaller data items being processed
- Speed of input
- Validation, length, range and format checks
- Presentation
- Confidentiality, data maybe meaning less without knowledge of coding method
- Dis-advantages
- Interpretation, B75 is Birmingham or Brighton
- Accuracy, data entry requires every character to be legible
- Completeness, some data can be lost
- Limited codes, codes can run out
- Value judgement, someones 9 might be different to someones 6, people interpreter things differently.
- Replacing data with shorter data
- Check Digit
- Indirect
- Gathered from another source or as a by product of another operation
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