Learning..Simple variable as text in texteditor

Question

I'm trying some basic things to learn. I just want the result from vari3 in the text document. But I get an apple event error.on this part 'set text 1 to vari3'
Please also give a bit advice... so I learn from it. many thanks.
I did try some changes but don't know what the best solution.
'set text 1 to "It works" Will work because that's plain text.
But getting the variable will not work for me.
set vari1 to 1 + 1
set vari2 to 1
set vari3 to vari1 + vari2
tell application "TextEdit"
activate
make new document at beginning
tell document 1
set text 1 to vari3
end tell
save the front document in ":Users:X:Desktop:testing.rtf" with replacing
close the front document
end tell
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Answer 1

This is a strange issue of coercion.
TextEdit should be able to automatically coerce vari3 into a text object, but it fails for some reason. The solution is to be explicit.
Just change the line:
set text 1 to vari3
to:
set text 1 to vari3 as text
Off-hand, it isn't clear to me why this is necessary.