Numbers and maths

Maths like a calculator

• JavaScript does maths with + - * /.
• There is only one kind of number, so / can give a decimal: 7 / 2 is 3.5.

console.log(7 + 2);   // → 9
console.log(7 / 2);   // → 3.5

Remainder and powers

• % gives the remainder after dividing: 23 % 5 is 3 (5 goes in 4 times, 3 left over).
• ** raises to a power: 2 ** 5 is 2 × 2 × 2 × 2 × 2.

console.log(23 % 5);   // → 3
console.log(2 ** 5);   // → 32

Order of operations

• * / % happen before + and - — the same rules as in maths class.
• Use brackets ( ) to force what should happen first.

console.log(2 + 3 * 4);     // → 14  (the 3 * 4 first)
console.log((2 + 3) * 4);   // → 20  (the brackets first)

Common mistakes

• % is the remainder operator; / can give a decimal.
• "3" + 4 gives "34" (a string), not 7.

Now you try

• Use the maths operators.
• Press Check answer to test it.