Mathematical symbol:?

Meaning: If one number A is added to another number B, and the approximate value of the sum is equal to A, then A? b

If a is more than 3 orders of magnitude larger than b, it is generally considered that a? b

Nature: if a? B can be ignored in inaccurate summation calculation.

Attachment: magnitude refers to the scale or size of quantity, and a fixed proportion is maintained between each level. Commonly used ratios are10,2, 1000, 1024, e.

In real life, unless otherwise specified, orders of magnitude are generally based on10 (the power of10).