Add some fun to estimating with a little friendly competition, or individual quickness. This activity is designed to increase student automation with rounding numbers to the nearest TENS place. Students will spread out the 10 category cards (10 - 100), leaving room to place cards underneath (think Solitaire). They will shuffle the number cards up and place them in a stack upside down. Drawing one card at a time, they will place it under the category card that it belongs, as fast as they can. Whe