### Home > MC1 > Chapter 9 > Lesson 9.2.1 > Problem9-59

9-59.

Each problem below has an error in the answer. Find the error, explain how to correct the mistake, and correct it. In parts (a) and (d), the X means to multiply.

1. $\left. \begin{array}[t] { r } { 10 } \\ { \times 0.5 } \\ \hline 50 \end{array} \right.$

Where should the decimal point be?
Does $50$ make sense as an answer?

1. $\left. \begin{array}[t] { r } { 467.92 } \\ { + 1.293 } \\ \hline 479.85 \end{array} \right.$

Here is a similar problem:

1. $\left. \begin{array}[t] { r } { 100 } \\ { - 62.837 } \\ \hline 38.837 \end{array} \right.$

Make sure that like parts are being added (tenths to tenths, hundredths to hundredths, etc.).
Lining up the decimal points can help to keep track of like parts.

1. $\left. \begin{array} { r } { 1.234 } \\ { \times 0.003 } \\ \hline 0.3702 \end{array} \right.$

Thinking about the denominators of the fractions can help make sense of where the decimal point should be.

What happens if you multiply  $1\frac{234}{1000}$ by $\frac{3}{1000}$?

1. $\left. \begin{array}[t] { r } { 4006.3 } \\ { - 34.98 } \\ \hline 3971.48 \end{array} \right.$

$3971.32$

1. $\left. \begin{array} { r } { 45.6 } \\ { 32.87 } \\ { + 0.003 } \\ \hline 374.6 \end{array} \right.$

Make sure that you add like parts.
Remember that lining up the decimal points can help to keep track of like parts.