Lesson 13 Analyze Addition Mistakes

- Let’s use place value strategies to add decimals.

Warm-up Estimation Exploration: Many Places

$1, 987.89 + 658.54$

Record an estimate that is:

too low	about right	too high

Activity 1 Compare Calculations

Find the value of $621.45 + 72.3$ . Explain or show your reasoning.
Elena and Andre found the value of $621.45 + 72.3$ . Who do you agree with? Explain or show your reasoning.

Activity 2 Same Digits, Different Sums

Find the value of each expression. Explain or show your reasoning.

$2.63 + 7.74$
$26.3 + 774$
$46.3 + 31.42$
$463 + 3.14$

Practice Problem

Problem 1

Find the value of the expression $215.7 + 64.94$ .