Multiplying Whole Numbers by Decimals
3 × 0.4
1.2
5.0 × 0.1
0.5
0.2 × 0.3
0.06
A student says 4 × 0.5 = 4.5. What is the mistake?
They added 4 + 0.5
A pencil is $0.50. What is the cost of 4 pencils?
$2.00
6 × 0.5
3
4.2 × 0.1
0.42
0.4 × 0.5
0.2 or 0.20
A student solved 6 × 0.2 by writing 6 × 2 = 12 and placing the decimal at the end. What did they do wrong?
The decimal should've been place in between the 1 and the 2
A ribbon is 0.25 meters long. What is the length of 6 ribbons?
1.5 meters
8 × 0.25
2
6.2 × 0.01
0.062
1.2 × 0.4
0.48
A student says 0.3 × 0.4 = 1.2. What should the correct answer be and why?
0.12 because there should've been 2 digits after the decimal.
Each cookie uses 0.4 cups of flour. How much flour is needed for 8.5 cookies?
3.4 cups
12 × 0.6
7.2
3.45 × 0.1
0.345
2.5 × 0.6
1.5 or 1.50
A student says 1.2 × 0.3 = 3.6 because 12 × 3 = 36 and you bring the decimal down so it's 3.6. What did they do wrong?
You don't bring the decimal down, you move it over to match the decimal places in your factors.
Answer : 0.36
A runner jogs 1.25 miles each day. He averages 10.2 runs a month. On average, how many miles does he run a month?
12.75 miles
A notebook costs $0.75. What is the cost of 16 notebooks?
28.6 × 0.01
0.286
3.24 × 0.8
2.592
A student uses a calculator and multiplies 2.5 × 0.6. The calculator says 1.5. She says the calculator must be broken because if there are 2 digits after the decimal in her factors, there should be 2 in her product. Explain what's wrong with this thinking.
Her answer should be 1.50, which has 2 digits after the decimal. The 0 isn't needed, so we can just write 1.5
1.5 = 1.50
A garden has 0.75 rows of flowers. Each row is 2.4 meters long. What is the total length of flowers planted?
1.8 meters or 1.800 meters