# Using the mod function to marks school work

I am quite new to computational layre in Desmos, and haven’t got any experience coding, but thrust into online maths teaching in this lockdown in the UK.

I am trying to create a question that self marks,which is “write three multiples of 12 and 18” such that students will get a comment saying well done for three correct and unique multiples.

I tried doing something like this but can’t seem to get it to work:
check1=numericValue(input2a.latex)
check2=numericValue(input2b.latex)
check3=numericValue(input2c.latex)

check1t= ("\mod(check1, 12 ) =0 , Mod(check1, 18) =0")
check2t= ("\mod(check2, 12 ) =0 , Mod(check2, 18) =0")
check3t= ("\mod(check3, 12 ) =0 , Mod(check3, 18) =0")

isCorrect = check1t and check2t and check3t and not(check1t=check2t) and not(check1t=check3t) and not(check2t=check3t)
correct: isCorrect
otherwise “Find three numbers that are multiples of 12 and 18.”

Could anyone give me a bit of help. Probably something very basic, but I’m finding this pretty tough

Computations in CL need to use numericValue or simpleFunction( ).evaluateAt( ). The latter apparently more consistent if decimals are involved. I’d do this, using LCM=36 instead of two separate mods:

``````check1 = numericValue(`\mod(\${input2a.latex},36)`)=0
check2= numericValue(`\mod(\${input2b.latex},36)`)=0
and not(input2a.numericValue=input2b.numericValue)
check3= numericValue(`\mod(\${input2c.latex},36)`)=0
and not(input2a.numericValue=input2c.numericValue)
and not(input2b.numericValue=input2c.numericValue)
isCorrect=check1 and check2 and check3
correct: isCorrect
``````

For the dashboard to mark correct, this needs to be in one of the inputs. And, the other two inputs need to have “readOnly: true” in their CL.

For feedback in a note, you can refer to “isCorrect” like this (assuming you put the above code in input2a:

``````content: when input2a.script.isCorrect "Good Job"
otherwise "Find three numbers that are multiples of 12 and 18."
``````

I had a slightly different idea than Daniel_Grubbs, but it will do the job, too. I added a couple of variables so that this could be duplicated and changed a little more quickly for a different pair of numbers.

https://teacher.desmos.com/activitybuilder/custom/601d6ef73ac5950d5da18af0