The expression doesn't work

[Vasily]

@Taifun

then you can use the split block and split at empty string to get a list of 2 items, the number 2150 and the mm , for the comparison just use the first item using the select list item block

The word “mm” is not written to the textbox. The default Hint field is " Enter in mm". The Input Type is set to the value “Number”.

[Taifun]

@Vasily

Here is the solution. TextBox (2,3,4) , in addition to text box 1, hidden

a simple problem resulted in a complicated solution with loads of blocks…
this does not have to be like that…

@Vasily

The Input Type is set to the value “Number”.

so what exactly prevents you from using the < or > block to compare numbers?
https://docs.kodular.io/blocks/math/#lt

Taifun