standard_description: Write simple expressions that record calculations with numbers, and interpret numerical expressions without evaluating them. For example, express the calculation “add 8 and 7, then multiply by 2” as 2 × (8 + 7). Recognize that 3 × (18932 + 921) is three times as large as 18932 + 921, without having to calculate the indicated sum or product.
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