330,000,000,000,000,000,000,000 mass using a one-digit whole number times a power of 10.

Step-by-step explanation:

330,000,000,000,000,000,000,000 has 22 zeros, so we can immediately say

33x10^22

This should be expressed using just a single decimal point, so we can move the decimal point two more spaces to the left, and add 2 to the exponent:

3.33x10^23

The question states a one digit whole number, so make it 3x10^23, although it seems an insult to the 0.33.  Go with the one you prefer.