Question

in this section, youll solve word problems by applying regrouping to add multi-digit numbers.

mya says she has calculated the total cost of the car ($23,829) along with the additional upgrade options ($1,099).

she provides documentation of her addition, shown here:
$20,000 + 3,000 + 800 + 20 + 9$
$+\underline{\\ \\ \\ \\ 0 + 1,000 +\\ \\ \\ 0 + 90 + 9}$
$20,000 + 4,000 + 800 + 110 + 18$

$20,000 + 3,000 + \overset{10}{800} + \overset{1}{20} + 9$
$+\underline{\\ \\ \\ \\ 0 + 1,000 +\\ \\ \\ 0 + 90 + 9}$
$20,000 + 4,000 + 810 + 11 + 8$
$20,000 + 4,000 + 810 + 11 + 8 = \\$24,829$

what possible error did mya make when regrouping to add the expanded forms?

mya regrouped 1 instead of 100 into the tens place and regrouped 10 instead of 1 into the hundreds place.
mya regrouped 1 instead of 10 into the tens place and regrouped 10 instead of 100 into the hundreds place.
mya regrouped 1 instead of 100 into the tens place and regrouped 10 instead of 1,000 into the hundreds place.
mya regrouped 1 instead of 10 into the tens place and regrouped 10 instead of 1,000 into the hundreds place.

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Explanation:

First, analyze the correct regrouping for the addition:

1. In the ones place: $9 + 9 = 18$. This means we keep 8 in the ones place and regroup 1 ten (10) to the tens place.
2. In the tens place: $20 + 90 + 10 = 120$. We keep 20 in the tens place and regroup 1 hundred (100) to the hundreds place.

Mya's error: She wrote the regrouped values as 1 in the tens place and 10 in the hundreds place, which reverses the correct place value regrouping. She regrouped 1 instead of 10 to the tens place, and 10 instead of 100 to the hundreds place.

Answer:

B. Mya regrouped 1 instead of 10 into the tens place and regrouped 10 instead of 100 into the hundreds place.