Multiplication
Multiplication is another one of the four operations. Multiplication is the process of adding multiple sets of the same number. To multiply, we will take each place value and multiply it to every value in the other number. If the number being multiplied has more than one value, you must add a zero as a place holder each time you move to the next place value. This process continues until all of the places have been multiplied.
Back in the cookie shop, Val and Keri have finished their daily order. As they talk, Keri wonders if they cooked this many cookies daily, how many cookies would they cook in 126 days. To do this, she will need to multiply the daily cookie order of 715 by 126 days.
To start this problem, Keri needs to multiply the 6 by each of the values on top from right to left. If a value is greater than 9, the tens place will be carried to the next place and added to the multiplied value.
Six times 5 is 30, so we keep the zero and carry the 3.
Next, we multiply 6 times 1, which is 6, and then add the carried three to equal 9. The value 9 is written below.
Then, we multiply the 6 times the 7, which is 42. Since there are no additional places on top to be multiplied, we write the 42 below.
Next, we must multiply each place on top by the 2. Since we moved one place on the bottom, we will need to add a zero to the next line below. As we multiply the 2 to each value on top, we get 14300.
As we move to the next place to multiply, we must now add two zeros to the bottom because we have moved over two place values.
Next, we need to multiply the 1 by each value on the top, which gives us 71500.
The last step to multiplying is to add these values together from right to left. After adding these values, the product is 90,090. Keri knows that if they sell 715 cookies for 126 days, they will sell 90,090 cookies.
Division
The last of the four operations is division. Division is the process of taking a total value and dividing it into equal parts. The first step is to set up the problem. The value that is being divided is called the dividend, and the value that we are dividing into is called the divisor.
To set up a division problem, you will use the format dividend divided by divisor.
When dividing, we take the divisor and divide it into each value of the dividend from left to right. The number of times that the value will divide into the dividend goes on top. The value is then multiplied and subtracted from the dividend. The process continues until all of the places in the dividend have been divided. If there is a value that remains at the end, this is called your remainder.
The wonderful smell of cookies has now attracted customers to the cookie shop. Val and Keri are glad to see such a huge crowd. There are 12 customers that have gathered at the cookie counter. Val and Keri know that they have cooked only 715 cookies. Val wants to know how many cookies each of the 12 customers order.
In this problem, 715 is the dividend, and 12 is the divisor. The problem would be set up as 715 divided by 12.
The first step is to take the 12 and see which value it will divide into. 12 will not divide into 7, so we must use the first two values 71. Twelve will go into 71 five times. So, we write the 5 on top.
Next, we need to multiply the 5 times 12 which is 60. This value gets written below the 71 in the dividend.
Now, we must subtract 71 minus 60, which is 11. We must also bring down the next value from the dividend.
The new dividend is 115. Next, we must see how many times 12 will divide into 115, which is 9. This 9 gets written on top.
At this point, we repeat the same process as in the previous step. We need to multiply 9 times the 12, which is 108, which will be written below the 115.
Subtract 108 from 115, which is 7. Since we are out of values in the dividend, 7 is our remainder. Val can now see that he can sell each customer 59 cookies, and he will have 7 cookies leftover.