About Arithmetic Operators

Operators

Go supports the following arithmetic operators:

Operator	Example
+	4 + 6 == 10
-	15 - 10 == 5
*	2 * 3 == 6
/	13 / 3 == 4
%	13 % 3 == 1

For integer division, the remainder is dropped (e.g. 5 / 2 == 2).

The + operator also concatenates strings: "foo" + "bar" == "foobar".

Mixed-Type Arithmetic

Go does not allow arithmetic operations between different numeric types:

x := 42
n := 2.0
value := n * x // invalid operation: n * x (mismatched types float64 and int)

The operands must be the same type, sometimes requiring explicit conversion:

x := float64(42)
n := 2.0
value := n * x 

Shorthand Assignments

Each operator has a shorthand assignment form that updates the variable in place:

a := 1
a += 2 // same as a = a + 2 == 3

b := 2
b -= 2 // same as b = b - 2 == 0

c := 4
c *= 2 // same as c = c * 2 == 8

d := 8
d /= 2 // same as d = d / 2 == 4

e := 16
e %= 2 // same as e = e % 2 == 0

Increment and Decrement

When placed after a variable, the increment (++) and decrement (--) statements either increase or decrease its stored numeric value by 1. Placing them before a variable is a syntax error.

a := 10
a++ // same as a += 1, a == 11

b := 10
b-- // same as b -= 1, b == 9

Because they are statements, they do not return a value.

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Originally from Exercism go concepts