     func setOperand(operand: Double) {
         accumulator = operand
 //        description += String(operand)
-        descriptionCollection.append(String(operand))
+        if descriptionCollection.last == "√" || descriptionCollection.last == "=" {
+            descriptionCollection.removeAll()
+            descriptionCollection.append(String(operand))
+        } else {
+            descriptionCollection.append(String(operand))
+        }
         
         internalProgram.append(operand as AnyObject)
     }

        case Equals
    }
    
    func performOperation(symbol: String) {
        internalProgram.append(symbol as AnyObject)
        

            }
        } else if symbol == "=" && (descriptionCollection.filter{$0 == "="}).count >= 1 {
            descriptionCollection = descriptionCollection.filter{$0 != "="}
            descriptionCollection.append(symbol)
        } else if symbol == "=" && binaryOps.contains(descriptionCollection.last!) {
            descriptionCollection.append(String(accumulator))
            descriptionCollection.append(symbol)
        } else {
            descriptionCollection.append(symbol)
