9/23/17

number 17

Code: PU 
P=100 (k=83=15=-2 (mod 17) )
Formulae:
Number N is divisible by 17 iff 15*b+a = -2b+a is divisible by 17

Example:
Number N = 98 76 54 32 10 = 13 8 3 15 10 =
-2(  13 8 3 15)+10 =
-2(-2(  13 8 3+15)+10 =
-2(-2(-2( 13 8+3)+15)+10 =
-2(-2(-2(-2*13+8)+3)+15)+10 =
-2(-2(-2*   16+3)+15)+10 =
-2(-2*       5+15)+10
-2*          5+10 = 0 (mod 17)
is divisible by 17.



Code: PD
P=10, (k=7)
Formulae:
Number N is divisible by 17 iff -7b+a is divisible by 17

Example:
Number N = 54391
-7(      5439)+1 =
-7(-7(    543+9)+1 =
-7(-7(-7(  54+3)+9)+1 =
-7(-7(-7(-7*5+4)+3)+9)+1 =
-7(-7(-7*   3+3)+9)+1 =
-7(-7*   (-1)+9)+1
-7*      (-1)+1 = 8 (mod 17)
isn't divisible by 17.



Code: SF  12*10-7*17=1
12(10b+a) = b+12a (mod 17) 
Formulae:
Number N is divisible by 17 iff b+12a is divisible by 17

Example:
Number N = 68941
6894+12*1 = 6906
 689+12*8 = 762
  76+12*2 = 100
  10+12*0 = 10
isn't divisible by 17

This rule is equivalent the next one.



Code: SF-  5*10-3*17=-1
5(10b+a) = -b+5a = -(b-5a) (mod 17) 
Formulae:
Number N is divisible by 17 iff b-5a is divisible by 17

Example:
Number N = 67915
6791-5*5 = 6766
 676-5*6 =646
  64-5*6 = 34 = 2*17
is divisible by 17