Find the odd number from the alternatives given below:

To find the odd number, let's examine each option for a common pattern.

Check the sum of digits for each number:

Option 1: $3207 \rightarrow 3 + 2 + 0 + 7 = 12$

Option 2: $1308 \rightarrow 1 + 3 + 0 + 8 = 12$

Option 3: $2605 \rightarrow 2 + 6 + 0 + 5 = 13$

Option 4: $4026 \rightarrow 4 + 0 + 2 + 6 = 12$

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A number is divisible by 3 if the sum of its digits is divisible by 3.

For options 1, 2, and 4: Sum of digits = 12, which is divisible by 3

For option 3: Sum of digits = 13, which is NOT divisible by 3

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Checking divisibility:

$3207 \div 3 = 1069$ ✓

$1308 \div 3 = 436$ ✓

$2605 \div 3 = 868.33...$ ✗

$4026 \div 3 = 1342$ ✓

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Therefore, 2605 (Option 3) is the odd number as it is the only number not divisible by 3.