Читать книгу Basic Math & Pre-Algebra All-in-One For Dummies (+ Chapter Quizzes Online) - Mark Zegarelli - Страница 35

Stacked multiplication provides a systematic way to multiply a pair of larger numbers.

For example, to multiply , set up the multiplication as shown here, then begin by multiplying as follows:

Next, multiply . Because this result is more than one digit, place the 2 next to the 8 and carry the 1, as you would when adding:

Now, multiply , then add the 1 you carried, . This time, write the 9 below the line and carry the 2:

To finish the problem, multiply , then add the 2 you carried, , completing the problem as follows:

Therefore, .

When multiplying by a number that has more than one digit, multiply each digit in turn by the top number, and then finish by adding the results. For example, to multiply , begin by multiplying as follows:

Next, multiply :

Before moving on, notice that I have lined up this result, 658, with the multiplier, 7. To complete the problem, add these two results as follows:

Therefore, .