Home > CCAA > Chapter 3 Unit 2 > Lesson CC2: 3.3.2 > Problem3-109

3-109.

Each problem below has an error in the answer. Find the error, explain how to correct the mistake, and correct it.

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

The decimal point is in the wrong place. The answer should be $5.0$.

1.
$\array {\ \ 467.92\\\underline{+\ 1.293}\\ \ 479.85}$

The decimal points are not lined up. The answer should be $469.213$.

1.
${\ \ 100\\\underline{-\ 62.837}\\\ \ \ \ 38.837}$

The student did not add 0's to the 100 before subtracting. They also forgot to "borrow" when subtracting. The answer should be $37.163$.

1. $\array {\ \ \ \ 1.234\\\underline{\times \ \ \ 0.003}\\\ \ \ \ 0.3702}$

Look at part (a) for help. How many decimal places should there be in the answer?

1. $\array{4006.3\\\underline{-\ \ 34.98}\\\ 3971.48}$

Look at part (c) for help.

1. $\array{\ \ \ \ \ \ 45.6\\ \ \ \ \ 32.87\\ \underline{+\ 0.003}\\ \ \ \ 374.6}$

Look at part (b) for help. Can you quickly estimate what the answer should be close to?