Arithmetic, DIV and MOD

Arithmetic operators

• Pseudocode uses + - * / and ^ for the usual maths.
• / gives a real answer (with a decimal point).

OUTPUT 6 + 2      // → 8
OUTPUT 6 * 2      // → 12
OUTPUT 7 / 2      // → 3.5

^ raises to a power

• ^ means "to the power of". 2 ^ 10 is 2 multiplied by itself ten times, which is 1024.
• The syllabus lists it beside +, -, * and /.

OUTPUT 2 ^ 10       // → 1024

DIV: whole-number division

• DIV(a, b) divides and throws the remainder away.
• DIV(17, 5) is 3 — 5 goes into 17 three whole times.
• It is written like a function, with the two numbers in brackets — not between them.

OUTPUT DIV(17, 5)   // → 3

MOD: the remainder

• MOD(a, b) gives the remainder after dividing.
• MOD(17, 5) is 2. A number is even when MOD(N, 2) = 0.

OUTPUT MOD(17, 5)   // → 2

Watch out

• DIV and MOD work on whole numbers; plain / gives a decimal.
• Together they "undo" a division: DIV(17, 5) * 5 + MOD(17, 5) = 17.

Common mistakes

• DIV(a, b) is whole-number division; MOD(a, b) is the remainder. Both are written with brackets.
• Use brackets to control the order of arithmetic.

Now you try

• Use + - * / ^, and the functions DIV(a, b) / MOD(a, b).
• Press Check answer to test it.