97 lines
3.3 KiB
Plaintext
97 lines
3.3 KiB
Plaintext
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The following comes from Page 54 of Revenue Canada
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Taxation publication MC42. ( Jan 1,85. Machine
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computation of ......)
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Keith (PC1155)
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--------------------------------------------------
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The Social Insurance Number contains nine digits.
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The number consists of eight assigned digits, with
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the ninth digit being constructed from the first
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eight and acting as a check digit. The accuracy of
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transcription of the number may be verified using
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the standard modulus 10 check digit formula.
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Briefly, the check digit is established by
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considering the unit digit of the basic number and
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each alternate digit to the left to be a whole
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number. This number is multiplied by two and the
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digits in the product and the intervening digits
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which were not inflated are cross added. The sum
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is subtracted from the next highest number ending
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in zero. The difference is the check digit.
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For the purpose of verifying the Social Insurance
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Number, you must consider the basic Social
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Insurance Number which consists of the first eight
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digits. The example below may better illustrate
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the verication method.
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Check
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Basic No. Digit
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Social Insurance Number provided
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in your employee's record . . . . . . 123 456 78 2
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Make a number from unit position
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and each alternate position to the
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left . . . . . . . . . . . . . . . . 2 4 6 8
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Add the number to itself . . . . . . 2 4 6 8
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-----------
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Sum . . . . . . . . . . . . . . . . . 4 9 3 6
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Cross add the digits in the sum
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(4 + 9 + 3 + 6) = . . . . . . . . . . . . . . . . . . . . 22
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Cross add intervening digits
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(1 + 3 + 5 + 7) = . . . . . . . . . . . . . . . . . . . . 16
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---
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Total . . . . . . . . . . . . . . . . . . . . . . . . . . 38
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If the total is a multiple of 10, the check
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digit is 0, otherwise subtract from the next
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highest number ending in zero. . . . . . . . . . . . . . . 40
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Check digit is . . . . . . . . . . . . . . . . . . . . . . 2
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--------------------------------------------------
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Below is a BASIC code fragment that checks the number entered.
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Note that the number is a string.
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REM SIN$ IS THE NUMBER TO BE CHECKED
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820 FAIL = 0
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IF LEN(SIN$) <> 9 THEN FAIL = 1 : GOTO 830
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IF VAL(SIN$) = 0 THEN FAIL = 1 : GOTO 830
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REM GET ALTERNATE DIGITS
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X$="" : X=0
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FOR Z%=1 TO 4
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X$=X$+MID$(SIN$,Z%*2,1)
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NEXT Z%
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REM MULTIPLY BY 2
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X$=STR$(VAL(X$)*2)
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REM CROSS ADD THE DIGITS
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FOR Z%=1 TO LEN(X$)
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X=X+VAL(MID$(X$,Z%,1))
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NEXT Z%
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REM ADD THE INTERVENING DIGITS
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FOR Z%=1 TO 7 STEP 2
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X=X+VAL(MID$(SIN$,Z%,1))
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NEXT Z%
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REM SUBTRACT FROM THE NEXT MULTIPLE OF 10
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X=(10-(X MOD 10)) MOD 10
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REM CHECK THE RESULT AGAINST THE LAST DIGIT OF THE SIN$
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IF X <> VAL(RIGHT$(SIN$,1)) THEN FAIL = 1
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830 IF FAIL <> 0 THEN PRINT "BAD S.I.N. ";SIN$
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