@Override
	public boolean equals(Object obj) {
		if(obj == null) return false;
		if(!(obj instanceof NumberTop)) return false;
		NumberTop nt = (NumberTop) obj;
		
		if(this.number == null || nt.number == null){
			return this.number == nt.number;
		}
		
		return this.number.equals(nt.number);
	}