4 resources.
Logic gates for GATE CS and EC: truth tables for AND, OR, NOT, NAND, NOR, XOR and XNOR, NAND as a universal gate, a half adder, tracing a circuit, and common mistakes.
Boolean algebra for GATE CS and EC: the laws, De Morgan's theorems, the consensus theorem, simplifying algebraically and with a Karnaugh map, with worked examples and common mistakes.
The stack data structure for GATE CS: push and pop, overflow and underflow, evaluating postfix expressions, infix to postfix conversion, valid pop orders, and common mistakes.
Reading bar graphs for GATE General Aptitude: percentage change, averages, ratios and shares from one chart, with fully worked answers and common mistakes.