Certainly! Let's solve Lori's multiplication problem step-by-step to identify the mistake.
Lori was trying to multiply [tex]\(29 \times 31\)[/tex].
1. Write the numbers in vertical form for multiplication:
[tex]\[
\begin{array}{c}
& 29 \\
\times & 31 \\
\hline
\end{array}
\][/tex]
2. Multiply the bottom number 31 by the top number 29, starting with the rightmost digit of the bottom number (1):
[tex]\[
29 \times 1 = 29
\][/tex]
Write this product under the line.
3. Next, multiply the bottom number by the leftmost digit (3) of the bottom number 31. Remember to add a zero in the ones place before starting due to the place value:
[tex]\[
29 \times 3 = 87
\][/tex]
Placing a zero in the ones column because you are multiplying by the tens place:
[tex]\[
870
\][/tex]
4. Add the two products together:
[tex]\[
\begin{array}{c}
& 29 \\
+ & 870 \\
\hline
& 899 \\
\end{array}
\][/tex]
Thus, the correct multiplication result is:
[tex]\[ 29 \times 31 = 899 \][/tex]
Given Lori's incorrect answer of [tex]\(699\)[/tex], it is clear she made a mistake involving the multiplication steps.
Identifying the mistake:
Lori should have placed a 0 in the ones column before multiplying 3 by 9, which corresponds to multiplying by the tens place (30). She likely missed this step, leading to her incorrect result.
Thus, Lori's mistake was that she didn't
place a 0 in the ones column before multiplying [tex]\(3 \times 9\)[/tex].
The correct option is:
1. place a 0 in the ones column before multiplying [tex]\(3 \times 9\)[/tex].
