Computational Thinking - Riddle 1

What two whole, positive numbers that have a one-digit answer when multiplied and a two-digit answer when added?
riddle source: http://riddles.com/

How to?

We need to declare 2 variable sum and mult:

• sum is to check the sum of the 2 digits.
• mult is to check the multiplication of the 1 digit.

And both should be assigned as 0.

sum = 0 mult = 0 

Now we need 2 for loops to iterate through the needed numbers
The numbers should be between 1 and 9, beacuse their multiplication should be only 1 digit.
1-Any number multiplied by 0 will result 0

2-Any number less than 10 multiplied by 10 or a number greater than 10 will result to number of 2 digits

for x in range(1, 10): for y in range(1, 10): sum = x + y mult = x * y if(sum >= 10): if(mult < 10): print(str(x) + " and " + str(y)) break 

And finally we need to break the iteration at the end of the second loop to avoid iterating through the same numbers twice.

Answer

  > 9 and 1