count by 10’s, 100’s, and 1000’s;

http://www.oswego.org/ocsd-web/games/Ghostblasters1/gbcd.html

 http://www.freemathtest.com/FreeMathTest.asp?C=Sequences&MIN=0&MAX=700&STEP=100

http://www.freemathtest.com/FreeMathTest.asp?C=Sequences&MIN=0&MAX=7000&STEP=1000