The proper way to put a number in scientific notation is a specific way. So the answer you see above is the proper way you would put a number in scientific notation.
So. Put the decimal in between 3 and 4.
3.45000
Now count from the last 0 to 4. Which is 5. (Scientific notation can only be with 0's not any other number.)
The number of recycle bins that the city gives to citizens: 7204 : 2= 3602 The number of recycle bins is left: 7204 - 3602= 3602 The largest number of bins that can be given in each group: 3602 : 23 = 156 (residual: 14) => There are 14 bins left over.