Three significant figures.
The number, 22 billion, has 2 significant digits: 22.
15 000 894 written with 5 significant figures is 15 001 000, as the 894 rounds up to the nearest significant figure. 1.5001*10^7
Two
24000
Expressed in figures, this is equal to 500,000.
The number, 22 billion, has 2 significant digits: 22.
0,000 000 32 has only two significant figures (3 and 2).
2000*60=120 000 as 2000 is taken to have only one significant figure, we have a result of 100 000
15 000 894 written with 5 significant figures is 15 001 000, as the 894 rounds up to the nearest significant figure. 1.5001*10^7
It can be written as 1.00e6
Two
24000
55500000
29 792 458 in significant figures is 29 790 000, and written in scientific notation is 2.979*10^7
Measurements and calculations using very large or very small numbers will be very difficult. For example, 6.022 x 1023 (Avogadro's number) would have to be written out as 602 200 000 000 000 000 000 000. This can't be put into most calculators, so calculations would have to be done manually.
It is no more or no less significant that most other numbers.
One million = 1,000,000 in figures