When creating a histogram, identify the greatest and least values in the data set so that you can create measurement classes of
width
a. varying
c. skewed left
b. equal
d. skewed right

-- Think of positive numbers as floors in a building that are above ground level,
and negative numbers as floors in the building that are below ground level.
If you get good at picturing this, it will also get you through addition and subtraction.

-- For multiplication and division:

==>  Multiply or divide the two numbers just as if they had no plus or minus signs.
Aftet you finish the multiplication or division . . .

. . . . . If the two original numbers had the same sign ... either both positive or both negative ... then the answer is a positive number.

. . . . . If the two original numbers had different signs ... one positive and one negative  ... then the answer is a negative number.