Posted by Johnny on Sunday, November 6, 2011 at 12:01pm.
1.Estimate 45 x 56 using frontend.
2.Estimate 45 x 56 using rounding.

math  Ms. Sue, Sunday, November 6, 2011 at 12:08pm
1. 4 * 5
2. 50 * 50
http://www.aaamath.com/est73ax2.htm 
math  LaNesha, Thursday, January 5, 2017 at 8:56pm
Estimate 45 and 56 using frontend estimation