Q: How is the number 640,721 written in Scientific Notation?
A: 6.40721 x 105
The purpose of scientific notation is for scientists to write very large, or very small, numbers with ease.
Calculating scientific notation for a positive integer is simple, as it always follows this notation:
a x 10b
Follow the steps below to see how 640,721 is written in scientific notation.
To find a, take the number and move a decimal place to the right one position.
Now, to find b, count how many places to the right of the decimal.
| New Number: | 6 | . | 4 | 0 | 7 | 2 | 1 |
| Decimal Count: | 1 | 2 | 3 | 4 | 5 |
There are 5 places to the right of the decimal place.
Building upon what we know above, we can now reconstruct the number into scientific notation.
Remember, the notation is: a x 10b
a = 6.40721
b = 5
Now the whole thing:
6.40721 x 105
Check your work:
105 = 100,000 x 6.40721 = 640,721