Use plus or minus to make the following arithmetic operation correct: Five plus or minus five equals zero.
We can draw a model to help us find the answer. First, let’s try using the plus symbol. Five plus five equals zero. Is this true? So does five plus five equal zero? Let’s check: one, two, three, four, five, six, seven, eight, nine, 10. Five plus five makes 10.
So the missing symbol must be minus. Let’s check. So now we have five bricks. And we have to take away five. One take away two, three, four, five. Five take away five is zero. So the correct symbol is minus because five minus five equals zero.