2). weigh out why readings will vary that much?

Answer: the call is followed by a pushbutton switch, be sure to turn switch to KG location. when the screen display is zero, can be weighed. (Lb is the pound, ST is stone and is exported to Europe and the United States to use the weighing unit). If you do not pay extra attention to switch over to the pound, and mistaking kg counted, would have been called much worse than usual ... to appear on the so called "0.00KG", that can scale.

3.) what I weighed before and after weight will be different, are electronic scales have a problem?
A: electronic scale is by internal sensor weighing and display an incorrect. (you can put items in said repeatedly said, repeatedly shown that weight are the same, that is not a problem, because items you put the unstable situation does not exist.), so the construction of meaning parents said weight every time as far as possible to maintain the balance of goods, weighing keep items don't touch, numerically stable down in the read data in, in order to get more accurate data on weightLi Cheng