3.07 Decimals in the real world

Use the subtraction vertical algorithm to find how much change he will get back.

Set up the subtraction: \begin{array}{c} & &5 &.&0&0 \\ &- &3&.&2&0 \\ \hline \\ \hline \end{array}

0-0=0 so write a 0 below the last digit. \begin{array}{c} & &5 &.&0&0 \\ &- &3&.&2&0 \\ \hline &&&&&0 \\ \hline \end{array}

0 is less than 2 so we need to borrow from 5, to make it 10-2=8.\begin{array}{c} & &4 &.&{}^1 0&0 \\ &- &3&.&2&0 \\ \hline & & &.&8&0 \\ \hline \end{array}

Find 4-3=1.\begin{array}{c} & &4 &.{}^1 &0&0 \\ &- &3&.&2&0 \\ \hline & & 1&.&8&0 \\ \hline \end{array}

So the change due is \$ 1.80.

Use short division to find out how many bottles can be filled.

Set up the division.

38 can't go into 4, so 38 into 41 goes once remainder 3.

So we write 1 above 41 and carry the 3.

38 into 38 goes once, so write a 1 above the 8.

Write a 0 above the 0 at the end of the number.

The result is 110 bottles.

Use multiplication and subtraction vertical algorithm to find the temperature.

To find how much the temperature decreased by, multiply 2.34 by 4:

Set up the multiplication: \begin{array}{c} & &2 &. &3 &4 \\ &\times & & & &4 \\ \hline \\ \hline \end{array}

Multiply each digit by 4: \begin{array}{c} & & ^12\,\, & . & ^13\,\, & 4\\ & \times & & & & 4\\ \hline & & 9 & . & 3 & 6\\ \hline \end{array}

So the temperature will decrease by 9.36 \degree\text{C} in 4 hours. We need to subtract this from 29.6.

Set up the subtraction:\begin{array}{c} & &2 &9 &. &6 &0 \\ &- &0 &9 &. &3 &6 \\ \hline \\ \hline \end{array}

Subtract each digit from the left, borrowing when necessary:\begin{array}{c} & &2 &9 &. &5 &^{1}0 \\ &- &0 &9 &. &3 &6 \\ \hline & &2 &0 &. &2 &4 \\ \hline \end{array}

So the temperature will be 20.24 \degree\text{C}.