Format: Output

#f. Output format
12 spaces between the first letter of “Name” and “Grade”

print("Name %12s" % "Grade")
print("123456789012345678901234567890")
>>> 
Name        Grade
123456789012345678901234567890
>>>

The firs %10s is for “Name” right justified.
The second %10s is for “Grade” also right justified.

print("%10s%10s" % ("Name","Grade"))
print("123456789012345678901234567890")
>>> 
      Name     Grade
123456789012345678901234567890
>>>

The number 18129.06 has to fit in 10 spaces including the decimal
period, the two decimal digits after the period and right justified.

print("%10.2f" % (400.2 * 45.3))
print("123456789012345678901234567890")
>>> 
  18129.06
123456789012345678901234567890
>>>

The two floating point numbers has to fit in 10 spaces and right justified.

print("%10.2f%10.2f" % (400.2 * 45.3, 55*123.2))
print("123456789012345678901234567890")
>>> 
  18129.06   6776.00
123456789012345678901234567890
>>>

Let’s make use of the for loop, the range and the output formatting:

#g. Calculating compound interest

principal = 1000.00  # starting principal
rate = 0.5           # interest rate

print ("Year %21s" % "Amount on deposit:")

## 1234123456789012345678901
## Year    Amount on deposit:

for year in range (1,11):
    amount = principal * ( 1.0 + rate ) ** year # amount = principal * ( 1 + rate )^year
    print ("%4d%21.2f" % (year,amount))         # cool format to display a table 
##   %4d    is for a number of 4 digits for variable year
##   %21.2f is for a number of 21 positions: 18 digits, a decimal period and 2 decimal places

####################################################################################
# %21.2f indicates that variable amount is printed as a float-point value with a 
# decimal point.
# The column has a total field width of 21 character positions and two digits of
# precision to the right of the decimal point; the total field width includes the 
# decimal point and the two digits to its right, hence 18 of the 21 positions appear 
# to the left of the decimal point.
####################################################################################

print("1234123456789012345678.90")

##
##Year    Amount on deposit:
##   1              1500.00
##   2              2250.00
##   3              3375.00
##   4              5062.50
##   5              7593.75
##   6             11390.62
##   7             17085.94
##   8             25628.91
##   9             38443.36
##  10             57665.04
##1234123456789012345678.90