3rd Grade - Multiply With 4-Digit Numbers

Multiplication and Division
Multiply with 4-Digit Numbers
Solve simple problems involving multiplication of multidigit numbers by one-digit numbers
Number Sense: Simple Multiplication Problems The ability to multiply larger numbers by a single digit number. Ability to solve simple problems involving multiplication of multidigit numbers by one-digit numbers.

Sample Problems


When multiplying by tens, move the decimal point of the multiple of ten one place to the left, do the multiplication, move the decimal point of the answer (product) back one place to the right. For example, 8x50 would be 8x5=40=400.


Multiplying a two-digit number by a one-digit number: place the larger number above the other so the ones place digits are lined up. Draw the multiplication symbol and a line underneath the numbers. Multiply the ones place digits. Place the answer below the line in the ones place. Multiply the digit in the tens place column by the digit in the ones place of the second number. Place the answer below the line and to the left of the other number beneath the line. (Show an example: 32 x 2, 2x2=4, 4 is written below the line; 2x3=6, 6 is written below the line; 64 answer).


Define addend (a number added to another number) and factors (two or more numbers that are multiplied together to get an answer (product).


5 x 879= (4,395)


Hallie’s mom likes to bake in big batches. There are 8 cookie sheets in the large oven, each with twelve cookies. How many cookies did she make in all? (96 cookies)

Learning Tips


Some children may feel a bit intimidated by problems that have “all those numbers” when thus far their experience has mostly been with basic combinations of very simple multi-digit problems. Encourage them by pointing out that while there may be several multiplication steps needed, each time only two numbers are being multiplied together, and those will be combinations that the child already knows.


If problems are written horizontally (5 x 36) it is easier to solve them by writing them vertically, with the larger number on top. The smaller factor (5, in the example above) must be written directly below the ones digit of the top number (under the 6 in the example).


When multiplying a multi-digit number by a single-digit number, the first two numbers to multiply together are the digit in the ones place of the multi-digit and the single-digit number. Then the single-digit number is multiplied by the digit in the tens place of the larger number, and any regrouping issues are solved (i.e., remember to “carry” any leftover digits from the previous operation).


Children need to be very proficient in adding single-digit numbers to two-digit numbers because regrouping (carrying) is very common in multiplication. For this reason provide a lot of “mental math” experience for your child. Start with asking your child for the answers (calculated “in the head” without pencil/paper) to basic addition facts and then progress to adding small numbers to double-digit numbers, then on up to adding 9 to double-digit numbers. When children need to carry out a side-problem calculation to figure out the digits needed to regroup or “carry” mistakes are very common and once they are multiplying double-digit numbers by double-digit numbers, almost impossible to do off to the side as there is no room for so many little calculations.


Provide lots of practice and encouragement, but divide the problems into several small groups with a break in between. For most children learning this process it seems that there is a lot to keep track of and they tire quickly.


Continue to review any basic multiplication facts that are troublesome so that the need to stop and calculate the basic multiplication fact doesn’t impede your child’s trying to learn this new skill. If your child is still learning the basic combinations, supply those either verbally or on a multiplication chart so that your child is only trying to learn one new thing at a time. Work later on the combinations.

Extra Help Problems


4 x 456= (1,824)


8,902 x 3= (26,706)


5 times 80 equals (400)


A king had three daughters and they each picked a dozen roses in the garden. How many roses did they pick in all? (36)


A cookie tray has 5 kinds of cookies. There are 8 of each kind. How many cookies are there? (40)


Two fish live in a bowl. Each one can eat 9 flakes of fish food per day. How many flakes of fish food will Bill need to count out today so that his fish will have enough, but not too much food? (18)


A box has 100 puzzle pieces in it. Ann has 4 puzzles of this type. How many puzzle pieces does she have all together? (400)


A merry-go-round has 4 black horses in each section of the platform. There are 3 platform sections. How many black horses are there? (12)


There are 6 bags of jelly beans in Bob’s box. The label says that there are at least 42 jelly beans in each bag. What are the fewest jelly beans that he has? (252)


Tom, Jack, May, and Sarah each own a puppy. How many paws do their puppies have, altogether? (16; 4 children, 4 paws per puppy)


A gumball machine has 300 gumballs in it. Next to the gumball machine are 3 more just like it, but the colors of the gumballs are different in each. How many gumballs are in all of the machines together? No one has bought any gumballs yet. (1200)


Lina’s mom likes to put 6 flowers in each vase. There are 6 flower vases to fill. How many flowers must Lina cut from her flower garden? (36)


Jose plans to use old egg cartons as planters to start some seeds growing. He has 6 cartons saved up for this purpose. If he plants one seed in each section of the cartons, and all grow, how many plants will he have? (72)


Juan, Bill, Tyree, Sam, and Colin plan to start a club. They will want to have refreshments, so each boy agreed to bring 7 items of food to share with his friends. If they put all of these things on a table, how many items will there be on the table before anyone eats one? (5 boys x 7 items each =35 items)


Mr. Blake’s class is treated to ice cream. Each of the 22 children in the class is given a 2-scoop cone. How many scoops of ice cream were needed? (22 x 2=44)


90 x 9 = (810)


45 x 4 = (180)


86 x 9 = (774)


68 x 10 = (680)


27 x 9 = (243)


78 x 8 = (624)


44 x 4 = 176)


81 x 5 =( 405)


86 x 9 = (774)


72 x 8 = (576)


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