Find the sum of first five multiples of 7.

Options

A. 105
B. 135
C. 140
D. 153

Answer

To find the sum of the first five multiples of 7, we can follow these steps:

### Step 1: Identify the first five multiples of 7
The multiples of 7 can be found by multiplying 7 by the first five natural numbers (1 through 5):
- 1st multiple: \( 7 \times 1 = 7 \)
- 2nd multiple: \( 7 \times 2 = 14 \)
- 3rd multiple: \( 7 \times 3 = 21 \)
- 4th multiple: \( 7 \times 4 = 28 \)
- 5th multiple: \( 7 \times 5 = 35 \)

### Step 2: List the multiples
The first five multiples of 7 are:
- 7, 14, 21, 28, 35

### Step 3: Calculate the sum of these multiples
Now, we will add these multiples together:
\[ 7 + 14 + 21 + 28 + 35 \]

### Step 4: Perform the addition step-by-step
1. First, add the first two multiples:
\[ 7 + 14 = 21 \]
2. Next, add the result to the third multiple:
\[ 21 + 21 = 42 \]
3. Then, add the fourth multiple:
\[ 42 + 28 = 70 \]
4. Finally, add the fifth multiple:
\[ 70 + 35 = 105 \]

### Final Result
The sum of the first five multiples of 7 is \( 105 \).

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