http://www.i-programmer.info/babbages-bag/481-the-mod-function.html

%

O1000;

G17 G21 G90 G54 G40 G49 G80;

#100=10;

#101=30;

#102=21;

#103=19;

#104=45;

#105=4;

M06T1;

G43 H1;

M03 S1000;

N50 IF [#105 EQ 0] GOTO 100;

G00 X#101 Y#100 Z20.;

Z10.;

G01 Z-2.5 F120;

G91 X#104 F150;

G90;

G00 Z10.;

#105=#105-1;

#101=#101+#102;

#100=#100+#103;

GOTO 50;

N100 M05;

M09;

G91 G28 Z0.;

G28 X0.Y0.;

G90;

M30;