36 billion in scientific notation______ .
36 billion = 36 000 = 3.6 × 1010
258000 is expressed as ()
58 * (the 5th power of 10)
In scientific notation: 12.5 mg=______ Tons
5 mg = 12.5 △ 1000000000 = 1.25 × 10-8 tons, so the answer is 1.25 × 10-8