Number Decomposition: Breaking Down 7 into Units and Tens

To solve this problem, we will follow a straightforward analysis:

The number 7 is a single-digit number. In the decimal system, numbers are represented by their place values, which include units, tens, hundreds, and so on. When a number has only one digit, like 7, it occupies the units place.

This means that the entire value of 7 is placed in the units position. Therefore, the decomposition of the number 7 is simply:

• Step 1: Identify that 7 is a single-digit number.
• Step 2: Recognize that the digit 7 occupies the units place entirely.

Thus, the representation of the number 7 is entirely in the form of units, and we write it as $7 \text{ units}$.

Therefore, the correct choice from the options given is 7 units.