Examples with solutions for Multiplication of Decimal Fractions: Finding the decimal point

Exercise #1

Find the correct place of the decimal point:

1.35×2.47=33345 1.35\times2.47=33345

Video Solution

Step-by-Step Solution

To solve this problem, we will place the correct position for the decimal point in the product of 1.351.35 and 2.472.47.

Let's follow these steps:

  • Step 1: Identify the number of decimal places in the numbers being multiplied. 1.351.35 has 2 decimal places, and 2.472.47 also has 2 decimal places.
  • Step 2: Add these decimal places: 2+2=42 + 2 = 4. So, the product should have 4 decimal places.
  • Step 3: The given product without considering the decimal point is 3334533345. We need to position the decimal so that the product has 4 decimal places.

Now, let's work through applying these steps:
Step 1: 1.351.35 and 2.472.47 each contribute 2 decimal places.
Step 2: We sum 2+22 + 2 to get a total of 4 decimal places for the final result.
Step 3: Place the decimal point in 3334533345 so that there are four digits after the decimal point. This gives us 3.33453.3345.

Therefore, the correct placement of the decimal point in 3334533345 is 3.3345 \mathbf{3.3345} .

Answer

3.3345 3.3345

Exercise #2

Given the following exercise, find the correct place of the decimal point:

2.5×0.13=0325 2.5\times0.13=0325

Video Solution

Step-by-Step Solution

To solve this problem, we'll determine the placement of the decimal point, adhering to the total number of decimal places rule in multiplication:

  • Step 1: Identify the decimal places in the numbers.
    - 2.52.5 has 1 decimal place.
    - 0.130.13 has 2 decimal places.
  • Step 2: Calculate the total decimal places in the product:
    - Total: 1+2=31 + 2 = 3 decimal places.
  • Step 3: Apply the decimal places to the product 03250325:
    - Insert decimal point into 03250325 such that it reflects 3 decimal places:

Position the decimal to achieve 0.3250.325.

Therefore, the correct placement of the decimal point results in the answer 0.325 \text{0}.325 , matching the given correct answer.

Answer

0.325 \text{0}.325

Exercise #3

Given the following exercise, find the correct place of the decimal point:

3.751×0.5=18755 3.751\times0.5=18755

Video Solution

Step-by-Step Solution

To solve the problem, we need to follow these steps:

  • Step 1: Multiply 3.7513.751 and 0.50.5 as though they are whole numbers.
  • Step 2: Calculate the product of these whole numbers.
  • Step 3: Adjust the decimal point in the product to correspond to the number of decimal places in the original numbers.

Now, let's work through each step:

**Step 1-2**: Multiply 3.7513.751 by 0.50.5 by treating them as 37513751 and 55. The multiplication is:
3751×5=18755 3751 \times 5 = 18755

**Step 3**: The original numbers have a total of four decimal places (three from 3.7513.751 and one from 0.50.5). Therefore, the result should also have four decimal places. Starting with 1875518755, we place the decimal point four places from the right:
1.8755 1.8755

Thus, the correct result with the decimal point placed accurately is 1.87551.8755.

The correct answer brings us to choice 2: 1.87551.8755

Answer

1.8755 1.8755

Exercise #4

Given the following exercise, find the correct place of the decimal point:

6.13×2.05=125665 6.13\times2.05=125665

Video Solution

Step-by-Step Solution

To resolve the problem of finding the correct decimal point placement in the product of 6.13 6.13 and 2.05 2.05 , we proceed as follows:

  • Step 1: Calculate the total decimal places by adding the decimal places of each number.
    - The number 6.13 6.13 has 2 decimal places.
    - The number 2.05 2.05 has 2 decimal places.
    - Therefore, the total number of decimal places in the product should be 2+2=4 2 + 2 = 4 .

  • Step 2: Place the decimal point in the product number 125665 125665 to achieve 4 decimal places.
    - Starting from the right, count four places towards the left: 1256.65 1256.65 .
    - From 1256.65 1256.65 , adjust to achieve 4 places, resulting in 12.5665 12.5665 .

Thus, the correctly positioned product is 12.5665 12.5665 .

Answer

12.5665 12.5665

Exercise #5

Look at the following exercise and determine the correct place of the decimal point:

3.5×2.4=840 3.5\times2.4=840

Video Solution

Step-by-Step Solution

In the number -3.5, there is one digit after the decimal point: 5.

In the number 2.4, there is one digit after the decimal point: 4.

In other words, we have two digits after the decimal point.

Therefore we will move the decimal point two places to the left to get our answer: 8.40.

Answer

8.40 \text{8}.40

Exercise #6

Look at the following exercise and work out the correct place of the decimal point in the answer:

0.3×2.15=0645 0.3\times2.15=0645

Video Solution

Step-by-Step Solution

In the number -0.3, there is one digit after the decimal point: 3.

In the number 2.15, there are two digits after the decimal point: 15.

Therefore, we have three digits after the decimal point.

To find the answer, we will count three decimal places to the left, which gives us -0.645.

Answer

0.645 0.645

Exercise #7

Given the following exercise, find the correct place of the decimal point:

0.05×0.8=004 0.05\times0.8=004

Video Solution

Step-by-Step Solution

To solve for the correct placement of the decimal point in the product of 0.05×0.80.05 \times 0.8, follow these steps:

  • Step 1: Convert the multiplication to a format without decimal points by treating the numbers as whole numbers. Multiply 55 by 88 to get 4040.
  • Step 2: Count the total number of decimal places in the two factors. 0.050.05 has 2 decimal places, and 0.80.8 has 1 decimal place, summing it up to a total of 3 decimal places.
  • Step 3: Position the decimal point in 4040 to achieve 3 decimal places, making it 0.0400.040.

Thus, the product of 0.050.05 and 0.80.8 with the decimal point correctly placed is 0.0400.040.

Answer

0.040 0.040

Exercise #8

Given the following exercise, find the correct place of the decimal point:

0.10×0.10=001 0.10\times0.10=001

Video Solution

Step-by-Step Solution

To solve the problem of finding the correct place for the decimal point in the product 0.10×0.10 0.10 \times 0.10 , follow these steps:

  • Step 1: Identify the number of decimal places in each factor.
  • Step 2: Note that 0.10 0.10 has 2 decimal places, and 0.10 0.10 also has 2 decimal places.
  • Step 3: Add the decimal places from both factors: 2+2=4 2 + 2 = 4 .
  • Step 4: Calculate the product treating them as whole numbers: 10×10=100 10 \times 10 = 100 .
  • Step 5: Place the decimal point in the product so that it has a total of 4 decimal places, resulting in 0.0100 0.0100 .
  • Step 6: Simplify 0.0100 0.0100 by removing the redundant zeros to get 0.01 0.01 .

Therefore, the correct placement of the decimal point in the product 0.10×0.10 0.10 \times 0.10 is 0.01 0.01 .

Answer

0.01 0.01

Exercise #9

Given the following exercise, find the correct place of the decimal point:

0.2×0.55=011 0.2\times0.55=011

Video Solution

Step-by-Step Solution

To address this problem, we must first carry out the multiplication between 0.20.2 and 0.550.55, removing the decimals temporarily to simplify the process and then adjust for them correctly in the final product.

Step 1: Convert the decimals to whole numbers.
Rewrite 0.20.2 as 22 (by multiplying by 1010) and 0.550.55 as 5555 (by multiplying by 100100).

Step 2: Multiply these whole numbers.
Calculate 2×55=1102 \times 55 = 110.

Step 3: Determine where the decimal point should be placed in the result.
- The original number 0.20.2 has 1 decimal place.
- The original number 0.550.55 has 2 decimal places.
Thus, the total number of decimal places required is 1+2=31 + 2 = 3.

Step 4: Apply these decimal places to the product.
Move the decimal point three places from the right in 110110 to get 0.1100.110.

Therefore, the correct placement of the decimal point in the product is 0.1100.110.

Consequently, the choice corresponding to this solution is:0.1100.110

Answer

0.110 0.110

Exercise #10

Given the following exercise, find the correct place of the decimal point:

0.45×3.14=1413 0.45\times3.14=1413

Video Solution

Step-by-Step Solution

To solve this problem, we need to determine the correct position of the decimal point in the product 14131413, which results from multiplying 0.450.45 by 3.143.14.

  • Step 1: Count the decimal places in each factor. The number 0.450.45 has 2 decimal places, and 3.143.14 has 2 decimal places.
  • Step 2: Sum the decimal places from each factor. The total number of decimal places is 2+2=42 + 2 = 4.
  • Step 3: Place the decimal point in the result 14131413 such that there are 4 digits following the decimal.

Therefore, the decimal point should be placed to give us 1.4131.413.

Given the provided choices, the correct option is: 1.4131.413.

Thus, the corrected and correctly formatted multiplication result is 1.4131.413.

Answer

1.413 1.413

Exercise #11

Given the following exercise, find the correct place of the decimal point:

2.35×7.6=1786 2.35\times7.6=1786

Video Solution

Step-by-Step Solution

To solve this problem, we'll follow these steps:

  • Step 1: Identify the decimal places in each number.
  • Step 2: Determine the total number of decimal places needed in the product.
  • Step 3: Adjust the product to include the correct number of decimal places.
  • Step 4: Select the correct answer from the choices based on this calculation.

Let's work through these steps:

Step 1: The number 2.352.35 has two decimal places, and the number 7.67.6 has one decimal place. This gives us a total of 2+1=32 + 1 = 3 decimal places needed in the product.

Step 2: Multiply the numbers as whole numbers: 235×76=17860235 \times 76 = 17860. Notice it seems like 17861786 in the problem statement, which lacks correct decimal placement.

Step 3: With a total of three decimal places needed in the result, we place the decimal point in 17861786 to make it 17.8617.86, adding those three decimal places.

Step 4: Compare this with the given options. The placement in option 2 is 17.86\text{\textbf{17.86}}, which correctly reflects the required three decimal places.

Therefore, the correct solution is \(\textbf{17.8617.86}\).

Answer

17.86 17.86

Exercise #12

Given the following exercise, find the correct place of the decimal point:

2.37×1.10=2607 2.37\times1.10=2607

Video Solution

Step-by-Step Solution

To solve this problem, we'll follow these steps:

  • Identify the number of decimal places in each factor
  • Sum the decimal places of the factors
  • Place the decimal point in the product accordingly
  • Confirm with the provided choices

Step 1: Let's determine the decimal places:
The number 2.372.37 has 2 decimal places.
The number 1.101.10 has 2 decimal places.

Step 2: Calculate the total decimal places:
The sum of the decimal places in both numbers is 2+2=42 + 2 = 4.

Step 3: Position the decimal point in the product:
The result of 2.37×1.102.37 \times 1.10 is displayed as 2607.
We need to place the decimal point such that the result contains 4 decimal places in total, starting from the rightmost digit.

Step 4: Apply the decimal adjustment:
Starting from the right, place the decimal point 4 places from the right: 2.6072.607.

Therefore, the correct position of the decimal point in the product is 2.6072.607.

Answer

2.607 2.607