Replace, then follow the order
A formula connects quantities: v = u + at gives the speed v after time t. Replace each letter with its value, in brackets, then use the order of operations.
- v = u + at, u = 4, a = 2.5, t = 6
- v = 4 + 2.5 × 6
- = 4 + 15 = 19
Multiplication happens before addition, so 4 + 2.5 × 6 is not 6.5 × 6.
Squares, halves and roots
- E = ½mv²: only v is squared. With m = 10 and v = 4: ½ × 10 × 16 = 80.
- A = ½(a + b)h: the bracket first, then halve and multiply.
- r = √(A/π): divide inside the root first. Use the calculator's π key and keep all the digits until the end.
Formulae on the calculator
Work out (4/3) × π × 2.5³ in one go, then round to 3 significant figures. Then work out √(150 ÷ π). Check that brackets go round the whole of A/π.