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This Number System question develops accurate interpretation and stepwise calculation for “Which number is even?”. The explanation preserves the original mathematical conditions, verifies 128, and identifies common errors involving signs, brackets, operation order, factors, remainders or fraction handling. The verified result is 128.
The verified answer is 128, option D. The question-specific working recorded with the item is: Even numbers divisible by 2.. The distractors 121, 123, 125 may arise from changing the order of operations, mishandling a negative sign, using an incorrect reciprocal, ignoring a divisibility condition, or rounding an exact value. An independent reverse-check again gives 128.
FAQ
Common questions and clear answers for this topic.
Translate the statement into integer, fraction or place-value relations and simplify systematically.
128, option D.
Changing operation order, losing a sign, or simplifying a factor where cancellation is invalid.
Substitute it back, estimate its magnitude, or recompute using an equivalent form.
Number System covers Natural Numbers (1,2,3), Whole Numbers (0,1,2,3), Integers, Rational Numbers (p/q form), Irrational Numbers (like pi and root 2), and Real Numbers. For competitive exams like SSC CGL and IBPS, focus on: divisibility rules, LCM and HCF, factors, prime numbers, and unit digit calculations.
Divisibility rules: Divisible by 2 - last digit even. By 3 - sum of digits divisible by 3. By 4 - last two digits divisible by 4. By 5 - last digit 0 or 5. By 6 - divisible by both 2 and 3. By 8 - last three digits divisible by 8. By 9 - sum of digits divisible by 9. By 11 - difference of alternating digit sums divisible by 11. Mastering these rules helps solve Number System questions faster in competitive exams.
