Two Thousand, Six Hundred Eight
I write 620 billion as 620 billion.
Sixteen point two billion is how I would write it.
You write 3.56 billion as 3,560,000,000.
40,300,000,000
It is: 2,608,000,000,000 = 2.608*1012
Two Thousand, Six Hundred Eight
It is 8 + 26*100 = 2608
Answer: 2608 km = 1620.536 mi.
I write 620 billion as 620 billion.
Sixteen point two billion is how I would write it.
You write 3.56 billion as 3,560,000,000.
40,300,000,000
Go North for 2608 units of length, then go East for 2608 units, then South for 2608 units and finally West for 2608 units. This completes a square route, covering a distance of 4x2608 = 10432 units of distance. The square root of 10432, on the other hand, is approx 102.14
260.8
As a number it is: 1,800,000,000 = 1.8 billion
Since you asked how I would write the number, the answer is 1031.