7.10 Story problems with multiplication or division

Multiply the numbers together as whole numbers then insert the decimal point.

Ignore the decimal point multiply the numbers together as whole numbers in a vertical algorithm. We first multiply 106 by 3 and then by the 4 in the tens column, and then add the results.

\begin{array} {c} &&1&0&6 \\ \times &&&4&3\\ \hline &&3&1&8& \\ + &4&2&4&0 \\ \hline &4&5&5&8 \end {array}

In 43\times 1.06 there are 2 decimal places. So we need to insert the decimal point so that there are 2 decimal places in our answer.

43\times1.06=45.58

Use short division.

6 goes into 9 once with 3 remaining, so we put a 1 in the tens column at the top and carry 3 to the units column.

6 goes into 32 five times with 2 remaining, so we put a 5 in the units column at the top and carry 2 to the tenths column.

6 goes into 24 four times with 0 remaining, so we put a decimal point and a 4 in the tenths column at the top.

92.4\div6=15.4

Multiply the mass of the tile by the number of tiles.

Ignore the decimal point and multiply the numbers togetherin a vertical algorithm.

\begin{array} {c} &&{}^17&{}^51&8 \\ \times &&&&7\\ \hline &5&0&2&6& \\ \hline \end {array}

7.18\times 7 has two decimal places, so we insert the decimal point in our answer so that it has two decimal places.

\text{Total mass} =50.26 \text{ kg}

Divide the number of hours by the number of episodes.

4 goes into 13 three times since 4\times 3=12. So there a remainder of 1.

So each episode is 3\dfrac{1}{4} hours long. \dfrac{1}{4} as a decimal is 0.25.

So each episode is 3.25 hours long.

Multiply the cost of each to book by the number of books bought then add the cost of the pencil case.

We will first multiply the cost of each book by the number of books ignoring the decimal point.

\begin{array} {c} &{}^21&{}^44&{}^18&2 \\ \times &&&&5\\ \hline &7&4&1&0& \\ \hline \end {array}

14.82 \times 5 has 2 decimal places, so we will place a decimal point in our answer so there are 2 decimal places. This gives us: 74.10.

We add our answer to the cost of the pencil case.

\begin {array} {c} &{}^17&4&.&1&0 \\ + &&6&.&3&6 \\ \hline &8&0&.&4&6\\ \hline \end {array}

So Adam spent \$80.46.