<p><span style="font-size:22px"><a href="https://www.prepswift.com/quizzes/quiz/prepswift-multiplication-the-choice-method" target="_blank">Multiplication: The "Choice" Method Exercise</a></span></p>
<p><strong>Notes</strong>:</p>
<ul>
<li>around 4 minutes into the video, assume that we can have only one flavour in the ice-cream.</li>
<li>around 6 minutes into the video, it says that the number of ice cream concoctions is 10 × 2<sup>6</sup> - 1 = 639. This is <strong>not </strong>quite right. The reason is that the video remarks that there is only one way of creating an ice-cream without choosing any toppings, while the question says that there are 10 different flavours of ice-cream. This means that we actually have 10 ways of choosing an ice-cream without a topping, and that the correct answer is 10 × 2<sup>6</sup> - 10 = <strong>630</strong>. </li>
</ul>