Since physical calculators are strictly prohibited, GATE provides an on-screen virtual scientific calculator. Key rules include: 1. It is operated using a mouse only (keyboard shortcuts are disabled). 2. It follows a specific input sequence where for many functions, you enter the number first and then the operator (e.g., for sin(30), you may need to enter 30 then press 'sin'). 3. It does not support complex numbers ($a + ib$), matrix operations, or solving quadratic equations directly; these must be solved manually. 4. It includes memory functions ($M+$, $M-$, $MR$) to store intermediate results, which is vital for long numerical answer type (NAT) questions to avoid rounding errors.