Rules for integers.
Adding: If the signs are the same, add them and put down the sign.
ex. -6 + -5 = -11
Adding if the signs are different, find the difference by subtracting
the smaller number from the bigger number, then write down the
sign of the bigger number.
ex. -12 + 7 = 12 - 7 = 5 put down the sign of the bigger number, so
it should be -5
Subtraction: Change the subtract sign to Add, and change the sign
of the 2nd number, then follow Addition rules.
ex. 7-(-9)= 7+(+9)= +16
For Multiply and Divide
All you have to remember is that if the Signs are the same,
the answer is Positive, and if the sings are different,
the answer is Negative.
ex. -6 x -7 = +42