225, 336, 447, 558,___, 7710

Options

A. 690
B. 660
C. 689
D. 669

Explanation

To find the missing number in the series: 225, 336, 447, 558, ___, 7710, we will analyze the pattern in the series step by step.

### Step 1: Identify the Pattern
Let's break down the numbers in the series:

- The first number is **225**.
- The second number is **336**.
- The third number is **447**.
- The fourth number is **558**.
- The fifth number is missing.
- The sixth number is **7710**.

### Step 2: Analyze the First Digits
Now, let's look at the first two digits of each number:

- **225**: The first two digits are **22**.
- **336**: The first two digits are **33**.
- **447**: The first two digits are **44**.
- **558**: The first two digits are **55**.

We can see that the first two digits are increasing by **11** each time (22, 33, 44, 55).

### Step 3: Predict the Next First Two Digits
Following the established pattern, the next first two digits should be:

- **66** (since 55 + 11 = 66).

### Step 4: Analyze the Last Digits
Now, let's look at the last digits of each number:

- **225**: The last digit is **5**.
- **336**: The last digit is **6**.
- **447**: The last digit is **7**.
- **558**: The last digit is **8**.

We can see that the last digits are increasing by **1** each time (5, 6, 7, 8).

### Step 5: Predict the Next Last Digit
Following this pattern, the next last digit should be:

- **9** (since 8 + 1 = 9).

### Step 6: Combine the Predictions
Now, we can combine our predictions for the missing number:

- The first two digits will be **66**.
- The last digit will be **9**.

Thus, the missing number is **669**.

### Conclusion
The missing number in the series is **669**.

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