Multiplying 3 digits by 2 digits

Objective: In this lesson you will learn how to multiply multi-digit numbers by using the standard algorithm.

Example: The factors of 6 are 1, 2, 3, and 6. Words to know Multiplication is the operation that uses repeated addition of the same number or combining of equal groups. Factors are numbers that are multiplied by another to find a product. Example: The factors of 6 are 1, 2, 3, and 6. Partial product is when multiplying by a multi-digit multiplier, the result obtained when a factor is multiplied by the value of one of the digits. Product is the answer to a multiplication problem

Those are really big numbers! How do you multiply 512 x 46 Those are really big numbers!

Product – The result when two numbers are multiplied. Review Product – The result when two numbers are multiplied. For Example: 4 x 5 = 20

Review cont. Multiplication is repeated addition. 32 + 32 + 32 + 32 + 32 32 x 5 Multiplication is faster!

Multiplying by powers of 10. Review cont. Multiplying by powers of 10. 36 x 10 = 360 36 x 100 = 3,600 36 x 1,000 = 36,000

A Common Mistake Multiplying each digit as if it represents a number of “ones.” It is important to remember the place value of each digit. 36 x 5 = 30 x 5 + 6 x 5

Lesson Multiply 512 x 46 First, we need to multiply 512 by 6. Then we need to multiply 512 by 40.

Adding a zero shows that we are multiplying by 10’s. Lesson cont. 512 x 46 3072 + 20480 23,552 Adding a zero shows that we are multiplying by 10’s. Next, we add the partial products

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Conclusion In this lesson you have learned how to multiply multi-digit numbers by using the standard algorithm