# 10-arithmetic-ops.py - Using arithmetic with event generators.¶

Arithmetic operators can be used with EventGenerator objects to control their behaviour (and change the pattern of the sequence of values).

Available operators are:

- : substraction

* : multiplication

/ : division

**: exponent

% : modulo (remaining of the division)

//: quantizer (returns te nearest multiple of its argument)

Arithmetic can be done with event generators as both operand and operator.

```from pyo import *

s = Server().boot()

# Half-semitone scale (the octave is divided in 24 equally-spaced steps).
# The integer (a semitone in midi note) is divided by 2, which mean that
# there are two values inside a single integer.
e = Events(
midinote=EventDrunk(list(range(48)), maxStep=-2) / 2.0 + 72,
beat=1 / 4.0,
db=-12,
attack=0.001,
decay=0.05,
sustain=0.5,
release=0.005,
).play()

# Quantize to multiples of a minor third.
e2 = Events(
midinote=EventCall(random.uniform, 60, 72) // 3,
beat=1 / 4.0,
db=-12,
durmul=1,
attack=0.001,
decay=0.05,
sustain=0.5,
release=0.005,
).play()

# EventGenerator as arithmetic operator. Kind of ostinato.
e3 = Events(
midinote=EventSeq([48, 50, 52]) - EventSeq([0, 2, 4, 6]),
beat=1 / 4.0,
db=-12,
durmul=1,
attack=0.001,
decay=0.05,
sustain=0.5,
release=0.005,
).play()

s.gui(locals())
```