To find \( 23.45 - 68.7 \) using the additive inverse, we can rewrite the subtraction as the addition of a negative number:
\[ 23.45 - 68.7 = 23.45 + (-68.7) \]
Now we need to calculate \( 23.45 + (-68.7) \).
To do this, we can combine the two numbers:
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Align the numbers for addition: \[ \begin{array}{r} 23.45 \
- (-68.70) \ \hline \end{array} \]
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Since we are adding a negative number, we can think of it as subtracting \( 68.70 \) from \( 23.45 \).
Now, we can perform the following steps:
- Convert \( 23.45 \) and \( 68.70 \) so that we can subtract:
Let's change \( 23.45 \) to have a matching decimal:
\[ 23.45 - 68.70 = 23.45 + (-68.70) \]
The calculation goes as follows (keeping in mind to borrow when necessary):
- The larger number \( 68.70 \) is subtracted from \( 23.45 \).
- Starting from the rightmost digit:
\[ \begin{array}{r} 23.45 \
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68.70 \ \hline \end{array} \]
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\( 5 \) (from \( 23.45 \)) cannot subtract \( 0 \) (so remains \( 5 \)).
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\( 4 \) cannot subtract \( 7 \) (borrow from \( 2\) making it \( 1\)):
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\( 14 - 7 = 7 \)
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\( 1 - 8 = -7\) (so we borrow making it \(11\): \(11-8 = 3\))
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now from \(1\) becomes \(0\) as we borrowed.
Resulting:
- \( -45.25 \) (which is obtained after full subtraction)
Thus, the result: \[ 23.45 - 68.70 = -45.25 \]
So, \( 23.45 - 68.7 = -45.25 \).