standard_description: Add and subtract within 1000, using concrete models or drawings and strategies based on place value, properties of operations, and/or the relationship between addition and subtraction; relate the strategy to a written method. Understand that in adding or subtracting three-digit numbers, one adds or subtracts hundreds and hundreds, tens and tens, ones and ones; and sometimes it is necessary to compose or decompose tens or hundreds.
problem_activity: Problem 1
For parts (a) and (b) below,
Solve. Show or explain your work.
Assess the reasonableness of your answer.
a.   910 × 233
b.   852 × 488
Problem 2
Damian’s work on a multiplication problem is shown below.
[IMG]
a.   Why is Damian’s answer not reasonable? Use estimation in your explanation.
b.   What mistake do you think Damian made? Why do you think he made that mistake?
c.   Find the correct product of 5,126 × 47.


aligns: no