If you don't need any inputs, labels would indeed suffice. Algorithmically, you could do the following:
var random1 = random number from 0 to 100
var random2 = random number from 0 to 100
var operation = random number from 0 to 2
switch(operation) {
case 0:
set operation label to '+'
display random1 + random2
break;
case 1:
set operation label to '-'
display random1 - random2
break;
case 2:
set operation label to '*'
display random1 * random2
break;
} I don't exactly remember VB all too well so just look up random number in the VB help files.