I have such problem:

I determine variable X in first string of the first sheet.
Next steps, I had written 2-3 sheets of formulas and see result of calculation far far away from first page.
Can I determine variable Y (last sheet) which determine X value (on start sheet) ?

Like as Excel: a1 cell = a1000; a999 = result; a1000 = value.


Reword: Can we change variable determined on first sheet from variable from last sheet?

Yes, it's possible.
If you determine X early in your document, using Y that isn't yet defined, then later you may define Y as many times as you want, and each time you will get new corresponding X.

X:=Y*2
Y:=5
X=10
Y:=10
x=20

Wrote

Reword: Can we change variable determined on first sheet from variable from last sheet?

VladimiR,

Not very clear: as you open Smath you have page 1 [that you name as you wish]
When you call "New page" you will have page 2 [that you name as you wish]
... and so on ...

If page 1 collects successively results from page 2,3,,,
in page 2 write to file the calculated Y
read back [rfile] in page 1 the last calculated value from page 2

In other words: each time you update Y in pages 2,3,,, and [writefile]
in page 2,3,,, it updates the Y stored in file that you read back in page 1.

At the top of each page [work sheet] re-identify for the same file directory.