‘Number’ input parameter can not be used by algorithms in Graphic Modeler

How to use graphical modeler in QGIS?

To start a model in QGIS, we have to open a graphical modeller window from Processing menu then select Graphical Modeler as shown in figure 2. An empty graphical modeller window will be opened as in figure 3. In the graphical modeller window, we can see some icons and menus.
 

How does graphical modeler make spatial analysis easier?

When working with a GIS, most analysis operations are not isolated, but rather part of a chain of operations instead. Using the graphical modeler, that chain of processes can be wrapped into a single process, so it is as easy and convenient to execute as a single process later on a different set of inputs.