lesson 4-13 example 2 2-5 example 2 find the product of 87 and 39. use the traditional...
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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.
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