Calculator errors account for many lost marks in IGCSE Physics. Knowing how to enter values correctly prevents mistakes.
Standard form
When a question gives a value like 3.2 x 10^8, enter it using the EXP or x10^x button, not by typing “x 10 ^ 8” as separate operations. On most scientific calculators, press: 3.2, then EXP, then 8. This enters the full value as a single number.
Squaring and square roots
Use the x^2 button for squaring. For square roots, use the square root button. When squaring a value in standard form, enter the full value first, then square it.
Example: (4.0 x 10^3)^2 = enter 4.0 EXP 3, then press x^2. The result is 1.6 x 10^7.
Division with brackets
When a formula has a product in the denominator, use brackets. For example, to calculate resistance R = V / I where V = 12 and I = 0.5 x 10^-3: enter 12 / (0.5 EXP -3). The brackets prevent the calculator from dividing 12 by 0.5 first and then multiplying by 10^-3.
Checking units
The calculator gives a number but not a unit. After every calculation, write the unit from the formula. If the answer seems unreasonably large or small, check whether you entered standard form correctly.
Rounding
Give your answer to the same number of significant figures as the data in the question, or to 2 or 3 significant figures if not specified. Do not round intermediate steps.
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