2-5Example 2

Find the product of 87 and 39. Use the traditional multiplication method.

1. Estimate.

90 × 40 = 3,600

2-5Example 2

Find the product of 87 and 39. Use the traditional multiplication method.

2. Rewrite the problem in vertical format.

87 × 39

2-5Example 2

Find the product of 87 and 39. Use the traditional multiplication method.

3. Multiply 9 times the digit in the ones column.

87 × 39

9 × 7 = 63

Write the tens digit above the tens column and the ones digit in the product under the ones column.

3

6

2-5Example 2

Find the product of 87 and 39. Use the traditional multiplication method.

4. Multiply 9 times the tens column.

87 × 39

3

6

9 × 8 = 72

Add the 6 tens to get 78.

78

2-5Example 2

Find the product of 87 and 39. Use the traditional multiplication method.

5. Multiply the value of the digit in the tens place times 7.

87 × 39

3

30 × 7 = 210

Write the hundreds digit above the hundreds column and the tens digit in the product under the tens column.

78

10

2

2-5Example 2

Find the product of 87 and 39. Use the traditional multiplication method.

6. Multiply the value in the tens column by 30.

87 × 39

30 × 8 = 240

Add 2 tens to get 260. Write the 26 in the hundreds place.

3

78

10

2,6

2

2-5Example 2

Find the product of 87 and 39. Use the traditional multiplication method.

7. Find the sum of the two products.

87 × 39

3

78

2,610

2

______ 3,393

+

2-5Example 2

Find the product of 87 and 39. Use the traditional multiplication method.

8. The product is 3,393. Compare to your estimate for reasonableness.