We use scientific notation as sometimes numbers are so so big, that it becomes inconvenient for us to write the actual number.
Step-by-step explanation:
For example, if you have 9 billion of something, you wouldn't want to write those 9 zeroes all the time.
When writing in scientific notation we count the number of decimal places to when we have one non-zero integer to the right of the decimal place. We then write that number and multiply it by ten to the number of decimal places you counted earlier.
