Shared data

Consider the following class with a single field:

class MyClass {

    private volatile long number = 5;

    public void setNumber(long number) {
        this.number = number;
    }

    public long getNumber() {
        return number;
    }
}

Thread A and Thread B have access to one instance of the class.

Thread A assigns a new value to the field of the instance.

instance.setNumber(10);

After this event, Thread B reads the value of the instance using the getter:

int number = instance.getNumber();

What value(s) might Thread B read from number?