Practice Scientific Calculator for GATE

In GATE you can only use an on-screen calculator, worked with the mouse. Practise that here: tap or click the keys, then try the eleven exercises below. Nothing you type leaves this page.

Unofficial practice calculator. Not affiliated with GATE, IIT or TCS iON. It has the same keys, in the same rows, and takes input the same way as the official virtual scientific calculator, but the styling is ours. Before the exam, practise on the official one too. The GATE 2027 brochure (section 7) says mock examination links “together with the virtual scientific calculator will be accessible through GATE 2027 official website”. As of Tuesday, 27 October 2026 they aren't there yet, so check the GATE 2027 website. Until then, the latest official mock tests are the GATE 2026 mock tests (EC mock test), which include the calculator.

 
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What this calculator has

  • Arithmetic: +, −, ×, ÷, mod, %, (, ), ±, |x|
  • Powers and roots: x², x³, xʸ, 1/x, √, ∛, ʸ√x, 10ˣ, eˣ, Exp
  • Logs: log, ln, log₂x, logᵧx
  • Trigonometry (Deg or Rad): sin, cos, tan, sin⁻¹, cos⁻¹, tan⁻¹
  • Hyperbolic: sinh, cosh, tanh, sinh⁻¹, cosh⁻¹, tanh⁻¹
  • Constants and factorial: π, e, n!
  • Memory: MS, M+, M−, MR, MC
  • Editing: ⌫, C, =

There is no nCr key and no complex-number mode. For combinations, work out n! ÷ (r! × (n − r)!); for complex numbers, handle the real and imaginary parts separately, or by hand.

How you enter things

  • Number first, then the function. To get sin 30, type 30, then press sin. A function acts on the number just typed, or on a whole bracket if you close one first: ( 3 ÷ 4 ) tan⁻¹.
  • Normal order of operations. 2 + 3 × 4 = gives 14.
  • Exp means “times ten to the power”. 2 Exp 3 = gives 2000, and 3 Exp 8 is 3 × 10⁸.
  • Watch out: there is no way to enter a negative exponent with Exp. 2 Exp ± 3 = and 2 Exp − 3 = both show 2e+2-3 and give 197, here and on the official calculator, while 5 Exp ± 2 = gives 500 there (the ± is ignored). Never press ± or − after Exp: for 2 × 10⁻³, type 0.002, or 2 ÷ 1000.
  • % takes two numbers: a % b gives b percent of a, so 50 % 50 = gives 25. 50 % = on its own gives 50. % binds tighter than + and −: 200 + 10 % 10 = gives 201.
  • Arithmetic is shown at full precision, as on the official one: 2 ÷ 3 = gives 0.6666666666666666. Round only at the end, to the decimal places the question asks for.
  • Function results come without floating-point noise: 30 sin gives 0.5 (not 0.49999999999999994) and 81 logᵧx 3 = gives 4, as on the official one.
  • Very large results switch to e-notation: 10 xʸ 21 = shows 1e+21.
  • logᵧx takes the number first, then the base: 8 logᵧx 2 = gives 3. ʸ√x works the same way, x first, then the root index: 8 ʸ√x 3 = gives 2.
  • Press the function before =. Type the number, then the function, then =. Pressing a function straight after = isn't reliable on the official calculator: in one check, π ÷ 3 = then cos in Rad left π/3 on the display.
  • Deg is selected at the start; press Rad for radians.
  • The top line shows the expression, the bottom line the current number or result.
  • Exam mode (on to start with) ignores the keyboard, because the official calculator's Help screen says “Keyboard operation is disabled.” Turn it off to use digits, + − * / ^ ( ), Enter, Backspace and Esc. Help shows the official Help screen's text.

Still to check on the official calculator

The keys, Deg by default, the order of operations, number-then-function input, Exp (including ± and − after it), % (including inside a sum), logᵧx, ʸ√x, full-precision arithmetic, noise-free function results, e-notation from 10²¹ and the Help text were checked on the official calculator. These weren't, so try them there before you rely on them:

  • Whether a result can be copied into the NAT answer box, or has to be typed on the keypad
  • The exact number of decimals shown for function results such as 2 log or 40 sin (here they are rounded to 15 significant digits, which removes only floating-point noise)
  • What ± or the minus key straight after Exp does for other numbers: 2 Exp ± 3 = gives 197 but 5 Exp ± 2 = gives 500, so there is no single rule (here, ± after Exp is ignored except for the confirmed 2 case, and the minus key starts a subtraction as in 2 Exp − 3)
  • What a function key does straight after = (in one check, π ÷ 3 = then cos in Rad left π/3 on the display; here the function is applied to the answer, so enter the number and the function before pressing =)
  • When it switches to scientific notation for very small results (here, as JavaScript does: below 0.000001; for large results, 10 xʸ 21 = showing 1e+21 is confirmed)

Eleven exercises, step by step

Each one is the kind of arithmetic a GATE EC numerical question needs. Press the keys in order on the calculator above and compare the display. For the NAT questions, round once, at the end, as the brochure advises.

  1. Order of operations

    Work out 2 + 3 × 4 in one go.

    Try it:

    • 2
    • +
    • 3
    • ×
    • 4
    • =

    Expected display: 14

    Like the official calculator, this one multiplies before it adds, so you don't need brackets here. Use them anyway whenever a numerator or denominator has more than one term.

  2. A power ratio in decibels

    An amplifier's output power is 250 times its input. Find the gain in dB: 10 log(250).

    Try it:

    • 1
    • 0
    • ×
    • 2
    • 5
    • 0
    • log
    • =

    Expected display: 23.979400086720403

    To two decimal places: 23.98 dB. For a voltage ratio, use 20 instead of 10.

    Type 250 first, then log: functions act on the number just typed.

  3. From decibels back to a ratio

    A -3 dB point: what fraction of the power is left? Find 10^(-3/10).

    Try it:

    • (
    • 3
    • ±
    • ÷
    • 1
    • 0
    • )
    • 10ˣ
    • =

    Expected display: 0.5011872336272722

    Bracket the exponent, then press 10ˣ: it acts on the whole bracket. ± after the 3 makes it negative.

  4. A small change in dB: divide first, then take one log

    A voltage gain rises from 1000 to 1001. Find the change in dB to four decimal places: 20 log(1001 ÷ 1000).

    Try it:

    • (
    • 1
    • 0
    • 0
    • 1
    • ÷
    • 1
    • 0
    • 0
    • 0
    • )
    • log
    • ×
    • 2
    • 0
    • =

    Expected display: 0.008681549586371861

    To four decimal places: 0.0087 dB.

    The official Help screen says log results are precise only up to 5 digits. Working it as 20 log 1001 − 20 log 1000 subtracts two numbers close to 60, so a log good to 5 digits leaves 0.0086 or worse. Dividing first and taking one log keeps the answer right.

  5. Powers of ten with Exp

    Find the wavelength of a 1.5 MHz wave: λ = 3 × 10⁸ ÷ 1.5 × 10⁶.

    Try it:

    • 3
    • Exp
    • 8
    • ÷
    • 1
    • .
    • 5
    • Exp
    • 6
    • =

    Expected display: 200

    200 m.

    Exp means "times ten to the power": 3 Exp 8 is 3 × 10⁸, one number, so the division needs no brackets. On the official calculator, 2 Exp 3 gives 2000.

  6. A natural log with a small time constant

    An RC circuit with RC = 4.7 × 10⁻³ s takes RC ln 2 to fall to half. Find 4.7 × 10⁻³ × ln 2.

    Try it:

    • 4
    • .
    • 7
    • ÷
    • 1
    • 0
    • 0
    • 0
    • ×
    • 2
    • ln
    • =

    Expected display: 0.0032577917486317416

    In milliseconds to two decimal places: 3.26 ms. Convert the unit before you round.

    Divide by 1000 for 10⁻³. Don't press ± after Exp: on the official calculator 2 Exp ± 3 gives 197, not 0.002, and this one does the same.

  7. An inverse tangent in degrees

    Find the phase angle of 4 + j3: tan⁻¹(3/4), in degrees.

    Try it:

    • Deg
    • (
    • 3
    • ÷
    • 4
    • )
    • tan⁻¹
    • =

    Expected display: 36.869897645844

    To one decimal place: 36.9°.

    Deg is the default, as on the official calculator. In Rad the same keys give 0.643501108793284, the angle in radians.

  8. A cosine in radians

    Find cos(π/3), with the angle in radians.

    Try it:

    • Rad
    • (
    • π
    • ÷
    • 3
    • )
    • cos
    • =

    Expected display: 0.5

    Function results are shown without floating-point noise, as on the official calculator (30 sin gives 0.5), so this is 0.5, not 0.5000000000000001.

    When an angle comes with π in it, it is in radians. In Deg these keys give 0.99983297945913, the cosine of 1.047 degrees.

  9. The square root of a sum

    A 100 Ω resistor in series with a 0.3 H inductor at 50 Hz. Find |Z| = √(100² + (2π × 50 × 0.3)²).

    Try it:

    • (
    • 1
    • 0
    • 0
    • x²
    • +
    • (
    • 2
    • ×
    • π
    • ×
    • 5
    • 0
    • ×
    • 0
    • .
    • 3
    • )
    • x²
    • )
    • √
    • =

    Expected display: 137.414133046715

    To one decimal place: 137.4 Ω.

    Close the outer bracket before pressing √, so the root takes the whole sum. x² after the inner bracket squares the reactance.

  10. Combinations without an nCr key

    How many ways can 2 of 6 bits be in error? Find 6C2 = 6! ÷ (2! × 4!).

    Try it:

    • 6
    • n!
    • ÷
    • (
    • 2
    • n!
    • ×
    • 4
    • n!
    • )
    • =

    Expected display: 15

    The official calculator has n! but no nCr, so work out n! ÷ (r! × (n − r)!). Keep the bracket round the bottom line: without it, 6! ÷ 2! × 4! gives 8640.

  11. Store a result and reuse it

    220 Ω and 330 Ω in parallel feed a divider with 100 Ω. Find R∥ = 220 × 330 ÷ (220 + 330), store it, then find 12 × R∥ ÷ (R∥ + 100).

    Try it:

    • 2
    • 2
    • 0
    • ×
    • 3
    • 3
    • 0
    • ÷
    • (
    • 2
    • 2
    • 0
    • +
    • 3
    • 3
    • 0
    • )
    • =
    • MS
    • 1
    • 2
    • ×
    • MR
    • ÷
    • (
    • MR
    • +
    • 1
    • 0
    • 0
    • )
    • =

    Expected display: 6.827586206896552

    To two decimal places: 6.83 V.

    MS stores the 132 at full precision, so nothing is rounded halfway. Copying an intermediate result by hand is the commonest way to lose the last decimal place.

More on answering in GATE

Sources: the GATE 2027 information brochure (section 7, pages 21 and 22), IIT Madras; the GATE 2026 mock test page, IIT Guwahati; and the official virtual scientific calculator, TCS iON, for the keys and input order. Last verified Tuesday, 27 October 2026. Studyloaf is not affiliated with GATE, any IIT or TCS iON.