Basically start with 10^2, that it 10 x 10, which is 100.
Then do 7.3 x 100, this is 730
Why? Because when you multiply by 100, you move the decimal place two to the right. If you were to multiply something by 1000, you’d move it three to the right. 10000, four to the right, etc
Hope this helps a bit, please give brainliest if possible