Adding numbers from an array into a single cell

Is it fixed like this?

Sub test()
    [f98:y98] = "=sum(f32,f42,f52,f62)"
End Sub

That was great, it worked . Thanks!

However I don't know how many cells I need to add, in this case there are four tables hence '=sum(f32,f42,f52,f62)'. It could vary from one to many tables before the 'Costs of Development and Operation' table. But I have the row numbers, is there any way I can generalise this sum function with some counting variable?