POWERS OF TEN
When you multiply a decimal by 10, the decimal point moves how many places to the right?
1 place
What is 3 × 0.2?
0.6
Estimate 3.8 × 4.9 by rounding.
20
What is 0.5 × 0.5?
0.25
A notebook costs $2.75. What is the cost of 4 notebooks?
$11.00
What is 0.56 × 100?
56
What is 4 × 1.3?
5.2
Estimate 7.1 × 3.9.
28
What is 0.4 × 0.2
0.08
A pack of stickers costs $1.25. What is the cost of 6 packs?
$7.50
What is 7.2 × 1,000?
7,200
What is 2 × 0.34?
0.68
Estimate 9.7 × 0.4.
4
What is 1.2 × 0.3
0.36
A bottle holds 0.75 liter. What is the amount in 8 bottles?
6 LITERS
What is 0.04 × 1,000?
40
Solve: 5 × 0.18
0.90
Estimate 5.3 × 2.8.
15
What is 3.2 × 0.15
0.48
A rope is 1.5 meters long. You cut 0.4 of it. How much is that?
0.6 meters
This is the rule students can use when multiplying by 10, 100, or 1,000.
count the zeros and move the decimal that many places to the right
In the expression 2 × 0.45 = 2 × (0.4 + 0.05), this property is being used.
distributive property
Why do we estimate before solving exactly?
to check if the answer is reasonable and catch decimal-point mistakes
What is 0.12 × 0.03
0.0036
A student says: “Since 0.3 and 0.02 are both small, 0.3 × 0.02 must be 0.6.” What is the correct product?
0.006