Posted: January 11, 2018
http://www.mathsisfun.com/numbers/estimation-game.php
https://www.theproblemsite.com/games/guess-it
http://www.mathopolis.com/games/estimate-add10s.php
http://pbskids.org/cyberchase/math-games/glowlas-estimation-contraption/
http://www.amblesideprimary.com/ambleweb/mentalmaths/guessthenumber.html
http://www.learnalberta.ca/content/me5l/html/Math5.html