# Calculate Mod and more in W|A

Posted 1 year ago
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 I want to calculate a MOD-11 check digit; and then do some additional calculations.I start with 12 integer variables a-l; some values are known a=5,b=6,g=6,h=5,k=7,l=9I calculate intermediate weighted sum as x=(a * 13)+(b * 12)+(c* 11)+(d * 10)+(e * 9)+(f * 8)+(g * 7)+(h * 6)+(i * 5)+(j * 4)+(k * 3)+(l * 2) Then calculate MOD-11 of that sum y=mod(x,11)Then calculate check digit z=11-yNow I do these two additional calculations: 9.812+((x * z)/1000)=11.288, 15.780-((x * y)/1000)=11.844 I was hoping this site can tell me values of c,d,e,f,i,j that makes this all work; but I get "Wolfram|Alpha doesn't understand your query" message with the following input: a=5,b=6,g=6,h=5,k=7,l=9,x=(a * 13)+(b * 12)+(c * 11)+(d * 10)+(e * 9)+(f * 8)+(g * 7)+(h * 6)+(i * 5)+(j * 4)+(k * 3)+(l * 2),y=mod(x,11),9.812+((x * z)/1000)=11.288,15.780-((x * y)/1000)=11.844 Did I do something wrong?
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Posted 1 year ago
 I think WolframAlpha has a limit on the number of characters that can make up any query.Your problem as you have shown it takes 192 characters to enter into WolframAlpha and I think that might be almost twice the length that seems to be acceptable.If I change your problem to be y=mod(x,11),9812+x*z=11288,15780-x*y=11844 then it immediately responds with a solution x=492, y=8, z=3.Perhaps you can use this as an example and see if you can get a solution to your actual problem.Sometimes if a problem takes too many characters to write it might be possible to solve one simpler problem and then use that solution as input to solve a second problem which gives you the desired answer.If as a second problem I give WolframAlpha solve 492=5*13+6*12+c*11+d*10+e*9+f*8+6*7+5*6+i*5+j*4+7*3+9*2 over the integers and I ask it to use i as a variable instead of the square root of -1 then it immediately responds that there is no solution over the integers.Please check all this very carefully to make certain that I have not made any mistake and have not misunderstood your problem.
Posted 1 year ago
 Thanks!! I guess "e" is also a special value so I changed all variables; I also know these are single digits. site seems to like 11a as short form of a*11 solve 492-(65+72+42+30+21+18)=11a+10b+9c+8x+5y+4z,a<10,b<10,c<10,x<10,y<10,z<10 But Wolfram could still not solve it; perhaps I made a typo. I solved manually 5,6,6,3,6,4,6,5,6,8,7,9
Posted 1 year ago
 It seems unusual that you are multiplying one of your variables by 11 and also working modulo 11. That would seem to allow any value for that variable.I am not sure your problem is described precisely enough for me to know I am trying to solve the correct thing.
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