### Video Transcript

A wood plank of length 4.5 feet was
cut into 0.25-foot pieces. Determine how many pieces of wood
there are.

The total length of the wooden
plank is 4.5 feet, and the lengths of the individual pieces is 0.25 foot. In order to work out how many
pieces of wood there are, we need to work out how many times 0.25 goes into 4.5. So we have the calculation 4.5
divided by 0.25. We’re, therefore, being asked to
divide one decimal number by another. Let’s think about how to approach this.

First, we can express this division
as a fraction: 4.5 divided by 0.25 is equivalent to the fraction 4.5 over 0.25. The difficulty of the form in this
division comes from the fact that we’re currently being asked to divide by a
decimal. We’d much prefer to divide by an
integer. What we’re going to do is find an
equivalent fraction where the denominator is an integer and therefore much easier to
divide by.

To convert the decimal 0.25 to an
integer, we need to multiply by 100, giving the integer 25. To ensure that the fraction remains
equivalent, we need to do the same thing to the numerator. So we also need to multiply 4.5 by
100, giving 450. The equivalent fraction is
therefore 450 over 25. And we’re now dividing an integer
by an integer.

Now there are different ways that
you could perform this division, but I’m first going to cancel down by a factor of
five as I know that both 25 and 450 are multiples of five. 25 divided by five is five, and 450
divided by five is 90.

So we now have the division 90
divided by five. Now you could run through your five
times table to work this out, or you could perform a short division. Five goes into nine one time with a
remainder of four. Five goes into 40 eight times with
no remainder. So 90 divided by five is equal to
18.

As the two fractions are
equivalent, the answer to this division is the answer to the original question. There are 18 pieces of wood.