You explicitly order to output a string constant with the string value
var every time. The current value of i is then automatically also converted to string and appended.
You cannot access the value of a variable by a string in place of the variable itself.
To achieve what you wanted you need to make the three values accessible by index. One way to do so would be:
myArray = Array(10, 20, 30)
For i = 0 to 2 'Arrays created by the standard function Array() start with index 0.
To make values accessible via string values used as names you need to create a structured variable of a different type. The names then are still strings viewed from Basic, not variables.
Pöease don’t miss to add the tag “basic” to your question. Even better you replace “calc” with “basic” because the question isn’t related to Calc.