Answer:
a) Scientific notation is written as a unit digit, that can have other digits after the decimal place, multiplied by 10 to the power of n, where n can be any integer number.
Then 25x10^0 is not scientific notation, because there are two digits at the left of the decimal point.
The scientific notation would be:
2.5x10^1
b) Why is this useful?
Because we divide all our measures in powers of 10.
For example, you know that 1 meter = 100c
But we can also write this as:
1m = 1.0*10^3 cm.
The use of scientific notation comes useful because we can have a fast read of the dimensions of our measure, and in another hand, is way easier work with the 10 as a base when we solve equations.
