Q: How is the number 21 written in Scientific Notation?

Why is 21 written as 2.1 x 10¹ in scientific notation?

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 10^b

Follow the steps below to see how 21 is written in scientific notation.

Step 1

To find a, take the number and move a decimal place to the right one position.

• Original Number: 21
• New Number: 2.1

Step 2

Now, to find b, count how many places to the right of the decimal.

New Number:	2	.	1
Decimal Count:			1

There are 1 places to the right of the decimal place.

Step 3

Building upon what we know above, we can now reconstruct the number into scientific notation.

Remember, the notation is: a x 10^b

a = 2.1

b = 1

Now the whole thing:

2.1 x 10¹

Step 4

Check your work:

10¹ = 10 x 2.1 = 21

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