18 thousand
18,000
First, let's review the rules of scientific notation. Your number in the scientific format will be from 0−10 multiplied by 10 to either the positive or negative power of a number. So, since your number is 18,000, and this is not in the 0−10 range, let's change it to 1.8000.
18,000.
1.8000
Your starting number, then, would be 1.8⋅10? power. To find the missing power, take a look at the decimal places of 18,000. and 1.8000. We moved the decimal point 4 places to the left in order to get the new number. However, you want the scientific notation to be an abbreviation to help you find the big number, your original number, 18,000. So, this means that you're instead going 4 places to the right. So:
1.8⋅104 = 18,000. because if you move the decimal place to the right 4 places, it gives you the original, larger number.
