Q: How is the number 90,721,390 written in Scientific Notation?
A: 9.072139 x 107
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 90,721,390 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: | 9 | . | 0 | 7 | 2 | 1 | 3 | 9 | 0 |
| Decimal Count: | 1 | 2 | 3 | 4 | 5 | 6 | 7 |
There are 7 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 = 9.072139 (Please notice any zeroes on the end have been removed)
b = 7
Now the whole thing:
9.072139 x 107
Check your work:
107 = 10,000,000 x 9.072139 = 90,721,390
| 90,721,388 | 90,721,389 | 90,721,391 | 90,721,392 |
| 9.0721388 x 107 | 9.0721389 x 107 | 9.0721391 x 107 | 9.0721392 x 107 |