Subtraction of Whole Numbers
Part – Whole Interpretation
•
For this interpretation we are looking at the whole and at part of a set or measurement.
•
We know what the whole is and we are trying to find a missing part (the part needed
to make the whole).
The following are three set model
problems that illustrate the partwhole interpretation:
(Change Unknown)
(Part Unknown)
(Start Unknown)
Mary has 5 marbles.
How many more does
she need to have 12
marbles altogether?
(i.e. part is known,
whole is known, how
much more is needed to
get to the whole?)
Mary has 12 marbles. 5
are blue and the rest are
red. How many of the
marbles are red?
(i.e. part is known,
whole is known, find
the other missing part)
Mary had some
marbles. John gave her
5 more. Now she has
12 marbles. How many
marbles did Mary have
to begin with?
(i.e. part known, whole
known. Beginning part
not known)
1
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•
For this interpretation we have one set or one measurement.
•
We remove objects from the set / decrease the measurement.
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 Spring '08
 Papalonie
 Subtraction

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