Appending a "%" to numbers from a string

I have an expression that is working in animating a percentage based on a slider control.

n=thisComp.layer("Null 1").effect("Pie Slice 2")("Slider")

nRound=Math.round(n*10)/10;

check = nRound % 1

if (check == 0){

""  + nRound  + ".0" + "%"

}else{

nRound

}

What I can't figure out is why the "%" only appears when the number is whole and not there constantly? After reading through Dan Ebbert page, he indicates that you can in fact add it (which I thought I did correctly) but only on the whole numbers. When it's animating through the "tenths" the % does not appear.

I'm sure it's something simple, but I can't figure it out.

Thanks for your help.