diff --git a/README.org b/README.org
index 93be764..497c9a5 100644
--- a/README.org
+++ b/README.org
@@ -22,6 +22,8 @@ cd examples
 make all
 #+end_src
 
+[[./examples/gcdgrid.png]]
+
 [[./examples/hsv.png]]
 [[./examples/gradient.png]]
 
diff --git a/examples/Makefile b/examples/Makefile
index 1523ca0..9c85025 100644
--- a/examples/Makefile
+++ b/examples/Makefile
@@ -1,5 +1,5 @@
 .PHONY: all
-all: checkers.png random_pbm.png random_pgm.png random_ppm.png gradient.png hsv.png
+all: checkers.png random_pbm.png random_pgm.png random_ppm.png gradient.png hsv.png gcdgrid.png
 
 %.pnm: %.bqn
 	bqn $< > $@
diff --git a/examples/gcdgrid.bqn b/examples/gcdgrid.bqn
new file mode 100644
index 0000000..6acf3ce
--- /dev/null
+++ b/examples/gcdgrid.bqn
@@ -0,0 +1,12 @@
+bqngraphics←"../"
+⟨Viridis⟩←•Import bqngraphics∾"colormaps.bqn"
+⟨HSVtoRGB⟩←•Import bqngraphics∾"colors.bqn"
+⟨PBM,PGM,PPM⟩←•Import bqngraphics∾"pnm.bqn"
+
+# https://susam.net/blog/gcd-grid.html
+GCDGrid←•math.GCD⌜˜↕
+
+•Out PBM 1≠GCDGrid 50
+#•Out PGM GCDGrid 20
+#•Out PPM {⌊255×HSVtoRGB⎉1⍉(360×𝕩÷1+⌈˝𝕩)∾(2∾≢𝕩)⥊1}GCDGrid 20
+#•Out PPM ⌊255×> Viridis¨ (⊢÷⌈´∘⥊) GCDGrid 20
diff --git a/examples/gcdgrid.png b/examples/gcdgrid.png
new file mode 100644
index 0000000..f2e3be1
Binary files /dev/null and b/examples/gcdgrid.png differ