MULTIPLICATION - WHOLE NUMBERS

(5TH GRADE STANDARDS OF LEARNING)

STANDARDS

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Multiply by a Single Digit Number

Multiplication is a short cut for addition.  For example when you multiply 284 x 7, this is equivalent to adding 284 seven times, or adding 7 two hundred and eight four times. 

 
Step 1: Suppose that we want to multiply 768 x 7.  Begin by writing the problem so that the ones line up vertically.  One number should be written above the other.

Step 2: Multiply the ones together.  7 x 8 = 56.  This is equivalent to 5 tens and 6 ones.  Place the 6 below the ones, and the 5 tens above the tens column.

Step 3: Multiply 7 x 6, then add 5.  7 x 6 + 5 = 47.  Write the 7 tens in the tens column and place the 4 hundreds above the hundreds column.

Step 4: Multiply 7 x 7 then add 4.  7 x 7 + 4 = 53.  There are no more digits in the top number so place the 3 in the hundreds column and the 5 in the thousands column.

Step 5: The final answer is 5376.  

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Multiplication by More Than One Digit Number

Step 1: Suppose we want to find 925 x 48.  Line up the numbers vertically as shown to the right.  Notice that the ones are lined up, and the tens are lined up.
Step 2: Multiply 8 x 5 = 40.  The 0 is the number of ones, while the 4 is the number of tens.  Place the 0 below the ones and the 4 above the tens.
Step 3: Multiply 8 x 2 and add 4.  8 x 2 + 4 = 20.  The 0 is the number of tens and the 2 is the number of hundreds.  Place the 0 below the tens and the 2 above the hundreds.
Step 4: Multiply 8 x 9 and add 2.  8 x 9 + 2 = 74.  the 4 is the number of hundreds and the 7 is the number of thousands.  Since there are no more digits in the top number place the 4 and the 7 in the hundreds and thousands columns, respectively.
Step 5: In the previous step we multiplied 925 x 8.  Now we are going to multiply 925 x 4.  The 4 here represents 40, that is we are multiplying 925 x 40.  The difference between 95 x 4 and 95 x 40 is that 95 x 40 is ten times as large as 95 x 4.  For this reason we place a 0 in the ones column.
Step 6: Multiply 4 x 5 = 20.  The 0 is the number of tens and the 2 is the number of hundreds.  Place the 0 in the tens column in the second row below the problem, and the 2 above the 2 in the tens columns.
Step 7: Finish the multiplication using the same methods as before, multiplying and carrying. 
Step 8: Add up the numbers in the two rows using the regular operations of addition.  The final answer is: 44,400

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THE PROGRAM

INSTRUCTIONS

Work the problems just as you would on paper. 

 

 

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Practice

 

Instructions for Program (Word document)

Select One, Two, or Three Digit Multiplication

 

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