*Use number sense or make an estimate to determine where the decimal point belongs in the product.

Question

5 x 3.4 = 17
Answer:

3.1 x 6.2 = 1922
Answer:

0.6 x 0.4 = 24
Answer:

1.8 x 1.9 = 342
Answer:

0.9 x 0.9 = 81
Answer:

Answer 1

To determine where the decimal point belongs in the products, let's analyze each multiplication:

1. 5 x 3.4:

   • Estimate: \( 5 \times 3 = 15 \) (approximately).
   • Actual product: \( 5 \times 3.4 = 17 \).
   • Answer: 17.

2. 3.1 x 6.2:

   • Estimate: \( 3 \times 6 = 18 \) (approximately).
   • Actual product: \( 3.1 \times 6.2 = 19.22 \).
   • Answer: 19.22 (not 1922).

3. 0.6 x 0.4:

   • Estimate: \( 0.6 \times 0.4 = 0.24 \).
   • Actual product: \( 0.6 \times 0.4 = 0.24 \).
   • Answer: 0.24 (not 24).

4. 1.8 x 1.9:

   • Estimate: \( 1.8 \times 2 = 3.6 \) (approximately).
   • Actual product: \( 1.8 \times 1.9 = 3.42 \).
   • Answer: 3.42 (not 342).

5. 0.9 x 0.9:

   • Estimate: \( 0.9 \times 0.9 = 0.81 \).
   • Actual product: \( 0.9 \times 0.9 = 0.81 \).
   • Answer: 0.81 (not 81).

Final Answers:

1. 17
2. 19.22
3. 0.24
4. 3.42
5. 0.81