Title
Collecting Stamps problem
Problem Statement
Jessica has an odd number of stamps in her collection. The sum of the digits in
the number of stamps she has is 12. The hundreds digit is three times the ones
digit. If she has between 1000 and 2000 stamps in her collection, how many
stamps does Jessica have?
Problem setup
Jessica has between 1,000 and 2,000
stamps in her collection. The number of stamps she has is an odd value. If
you add up the digits in the numbers of stamps she has, the sum will be 12.
The hundreds digit in the number of stamps she has is three times as large as
the ones digit. From this can we find how many stamps Jessica has in her
collection?
Plans to Solve/Investigate the
Problem
With the information presented in the
problem, I can logically solve the problem stepbystep. There will be a
bit of guessandcheck involved also.
Investigation/Exploration of
the Problem
There are four place values that need
to be filled in: ___ ___ ___ ___. The
ones place has to be occupies by an odd digit (1, 3, 5, 7, or 9). The only
possible choices for the ones digit are 1 and 3; any larger value will not allow
three times the value to be placed in the hundreds place.
If 3 is is the ones place, then 9 is
in the hundreds place making a total of 12 without putting any digits in the
tens or thousands places at all. This cannot be correct. Thus the
ones digit has to be 1, making 3 the hundreds digit.
There are two more place values to
fill in. The sum of these other two digits has to be 8 in order to add to
the 1 and 3 (sum = 4) for a fourdigit total of 12. The number of
stamps is between 1,000 and 2,000; this means that the thousands digit has to be
1. Anything greater would give a value greater than 2,000. The
missing digit in the tens place is 7.
The final number of Jessica's
collected stamps is 1,371.
Extensions of the Problem
>The number of stamps could be an
even number.
>The number of stamps could be
between 10,000 and 20,000.
>The sum of the digits could be 15,
20, etc.
Author & Contact
Rita J. Rogers
rrogers@rockdale.k12.ga.us
