(mumbles) difference for
each number line model.
For any subtraction
problem, the first value
is the minuend, the value being subtracted
is called the subtrahend.
The result of the subtraction
is called the difference.
When looking at a number
line model for subtraction,
the minuend or the first value is always
indicated by the arrow starting at zero,
in this case, the blue arrow.
Notice that the blue arrow starts at zero
and jumps to eight, which
means the first value
in the subtraction problem,
or the minuend, is eight.
Next, we know we have subtraction,
because the red arrow moves
from the right to the left,
or decreases the value of eight.
Notice how the red arrow starts at eight
and jumps back to three,
three is not the value
being subtracted, three is
the result of the subtraction,
which is called the difference.
Which means we know eight
minus the subtrahend
must equal three.
To determine the subtrahend,
we need to determine
how many units we moved left
from eight back to three.
Let's go ahead and count those units,
starting at eight, we move
left, one, two, three,
four, five units back to three,
which means the subtrahend is five,
or we are subtracting five from eight.
This number line models,
eight minus five equals three.
Looking at the second model, notice how
the arrows starting at
zero with a blue arrow,
starts at zero and jumps out to 17.
Notice how the number line
has labels every two units,
but tick marks every one unit.
So this tick mark here is 17,
again giving us the minuend.
Again, because the red arrow moves from
right to left, we know we are subtracting,
and notice how the red arrow starts at 17,
and moves back to what would
be 11 on the number line.
11 is not the subtrahend, 11 is the result
of the subtraction, or the difference.
Which means we know 17
minus the subtrahend
must equal 11.
To determine the value
subtracted, or the subtrahend,
we need to determine
how many units from 17
back to 11 indicated by the red arrow.
So we will go ahead and count those units,
from 17 we have one, two,
three, four, five, six units
back to 11, which means
the subtrahend is six,
or we are subtracting six from 17.
Giving us the subtraction
problem: 17 minus six, equals 11.
I hope you found this helpful.
