Make a simple 4x4 simple square grid with no subdivisions.

1 PICK A GRAPH PAPER

Choose Grid and tap "+" to create a new paper

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2 CUSTOMIZE SETTINGS
The easy way to create squares — 
Tap the icon beside the color bar on the popup.  The blue lock image to the left tells whether the horizontal and vertical axes are linked.  After being tapped, the icon will change to show the axes are locked as seen below.  The controls for the vertical spacing disappear because the horizontal and vertical controls are now linked to work together.

OTHERWISE: If you don’t link the controls, you can create squares by individually adjusting the horizontal and vertical controls until they are the same.

NOW, Increase the grid spacing until it is just 4 squares across. In this case, 1 3/4" did the trick.

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3  TWEAK GENERAL SETTINGS TO FINISH
Now, switch over to the Page Settings controls and adjust the page margins (blue dotted line) to center the grid on the page and "squeeze out" the last row so the grid is 4x4.

Increasing the bottom margin and also the left margin adjusted the grid to center it on the page.