Arithmetic Operators

Apex gives you four basic arithmetic operators for working with numbers. You will use them constantly, from adding up order totals to computing discounts.

Operator Precedence

Just like in math class, multiplication and division happen before addition and subtraction:

Integer result = 2 + 3 * 4; // 14, not 20

Apex evaluates 3 * 4 first and then adds 2. When you want a different order, use parentheses:

Integer result = (2 + 3) * 4; // 20

Parentheses are also a great way to make your intent obvious to other developers, even when they are not strictly required.

Mixing Integer and Decimal

When an expression mixes an Integer with a Decimal, the result becomes a Decimal so no precision is lost:

Decimal price = 9.99;
Integer quantity = 3;
Decimal subtotal = price * quantity; // 29.97 (Decimal)

Putting It Together

Here is a short example that computes an order total:

Decimal unitPrice = 4.50;
Integer quantity = 3;
Decimal shippingFee = 2.25;

Decimal total = unitPrice * quantity + shippingFee;
System.debug(total); // 15.75

Because * runs before +, the unit price and quantity are multiplied first and the shipping fee is added last, which is exactly what we want.