Question

Find the odd one out:
2, 6, 12, 20, 30, 42, 56

• A. 12
• B. 30
• C. 42
• D. 56

Hint:

Check properties like divisibility or formulas for the given numbers to spot the odd one out.

Answer 1

The Correct Option is D

Step 1: Check the pattern of the numbers:
\[ 2, 6, 12, 20, 30, 42, 56 \] Step 2: These correspond to the formula \( n(n+1) \) for \( n = 1, 2, 3, \ldots \) except 56.
Calculate each:
\[ 1 \times 2 = 2, \quad 2 \times 3 = 6, \quad 3 \times 4 = 12, \quad 4 \times 5 = 20, \quad 5 \times 6 = 30, \quad 6 \times 7 = 42, \quad 7 \times 8 = 56 \] Step 3: Check divisibility by 3:
6, 12, 30, 42 are divisible by 3; 2 and 56 are not. Since 2 is not listed as an option, the odd one out is 56 because it is not divisible by 3 while the others are.