How would you write 7,123,000 in scientific notation?

To write a problem in scientific notation, you want to start off with a decimal. 

There is no decimal shown here, so we are doing to take the decimal and put it at the far right of the problem.

So now we have 

1,123,000.

We are going to move the decimal to the left until we reach a number that is less than 10 and greater then 1. In this case count all the number you moved the decimal between.

7123000.
0
0
0
3
2
1
^ That is 6 numbers.

Now, we have, 

7.123,000

So now we write out the problem.

7.123 * 10 ^ 6

We do ^ 6 because we moved the decimal 6 times.

And we do 7.123, because that's our greater then 1 and less than 10 number.

Final answer;

7.123 * 10^6