Posted by dk on Thursday, January 20, 2011 at 6:38pm.
without multiplying, how do you know that the product of 399 and 48 is smaller than 20,722?

4th grade  bobpursley, Thursday, January 20, 2011 at 6:39pm
what is 50x400?

4th grade  dk, Thursday, January 20, 2011 at 7:24pm
20,000

4th grade  Ms. Sue, Thursday, January 20, 2011 at 7:30pm
Since 399 is less than 400 and 48 is less than 50, then obviously the answer must be less than 20,000. Right?

social studies  christina manley, Wednesday, February 2, 2011 at 8:37pm
the world in the 1400s

4th grade  Juan, Thursday, October 11, 2012 at 9:09pm
how can you show without multiplying that 4/9 is greater then 0.4