Q: How is the number 21,555,515 written in Scientific Notation?
A: 2.1555515 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 21,555,515 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: | 2 | . | 1 | 5 | 5 | 5 | 5 | 1 | 5 |
| 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 = 2.1555515
b = 7
Now the whole thing:
2.1555515 x 107
Check your work:
107 = 10,000,000 x 2.1555515 = 21,555,515
| 21,555,513 | 21,555,514 | 21,555,516 | 21,555,517 |
| 2.1555513 x 107 | 2.1555514 x 107 | 2.1555516 x 107 | 2.1555517 x 107 |