CPM Homework Help : ACC6 Problem 8-53

Maciel and Alejandro were trying to figure out the answer to $8.42+0.3$ . Maciel thinks the answer is $8.72$ , but Alejandro got $8.45$ . Who is correct? Why? What did the other person do wrong?

Hint:

Think about the meaning of $0.3$ . Does it mean $3$ tenths? $3$ hundreths? $3$ thousandths? Which part of $8.42$ has the same place value?

More Help:

$0.3$ means $3$ tenths. $8.42$ means $8$ wholes, $4$ tenths, and $2$ hundreths. Can you combine these values now?

Partial Answer:

Maciel is correct. Can you explain how Alejandro found the wrong sum?