RRB Technician Grade I 13 March 2026 Paper

Concept:An OR operation can be built using only AND and NOT gates with De Morgan’s Law: $X + Y = \overline{\overline{X} \cdot \overline{Y}}$.Explanation:Given: $F = ABC + DE$.Apply double inversion to keep the function unchanged: $F = \overline{\overline{ABC + DE}}$.Using De Morgan’s Law on the inner inversion: $\overline{ABC + DE} = \overline{ABC} \cdot \overline{DE}$.So, the function becomes $F = \overline{\overline{ABC} \cdot \overline{DE}}$.Now count the gates required.To form $ABC$: use two 2-input AND gates. First gives $AB$, second gives $(AB)C = ABC$.To form $DE$: use one 2-input AND gate to get $DE$.Invert both products: one NOT gate gives $\overline{ABC}$, another NOT gate gives $\overline{DE}$.Combine them using one more 2-input AND gate: $W = \overline{ABC} \cdot \overline{DE}$.Finally, invert $W$ with a third NOT gate to get $F = \overline{W}$.Total AND gates required: $2 + 1 + 1 = 4$.Total NOT gates required: $2 + 1 = 3$.This matches option D.Answer:4 AND gates and 3 NOT gates — Option D.