A binary operation * is defined on the set of real numbers by $a * b = a + b - 2ab$. Find the value of $3 * 2$.

Substituting a = 3 and b = 2 into the operation: 3 * 2 = 3 + 2 − 2(3)(2) = 5 − 12 = −7. Common errors include forgetting to multiply by 2 in the last term (giving 5 − 6 = −1) or computing 2ab as 2(3 + 2) = 10 instead of 2 × 3 × 2 = 12.