Opposite Change Rule for Addition Method
This method is best used when dealing with
two-digit numbers. The rule states: "If you
subtract a number from one addend, and add
the same number to the other addend, the sum
is the same."
Using this rule makes the problem more user
friendly by changing one of the addends so
that there is a zero in the ones place.
1. Add a number to one of the addends so that there will be
a zero in the ones place.
2. Subtract the same value you added to the previous
addend from the other addend .
3. Add (mental math should be all that is necessary).