Signed Number Nomograph
A nomograph is set of 3 parallel number lines and a 4th line
used to set up and complete an addition or subtraction.
This one is set up to show that the sum of -4 and +2 is -2.
- -4 the addend, is on the bottom line,
- 2 the addend, is on the top line,
- - 2, the sum, is on the middle line.
Components of a Nomograph
Each nomograph requires:
- A set of identical parallel number lines having scales lined-up one above the other.
- A middle or third number line placed parallel and midway between the first two.
- Each number on the middle number line is twice as large its corresponding
value on the outer number lines.
- A additional string or rigid line is needed to connect addends on the outer
lines and read the sum on the middle line.
- This rigid line must be able to reach from the left-most addend on the top line
-   to the
- right-most addend on the bottom line.
To Use a Nomograph to Add
- Stretch the rigid line from an added on the top line to the
other addend on the bottom line.
- Read the sum at the intersection of the rigid line and
the middle number line.
To Use a Nomograph to Subtract
- Stretch the rigid line from the subtrahend on the top line through the minuend on the middle line
then continue the line to the bottom line.
- Read the remainder at the intersection of the rigid line and
the bottom number line.
It Takes All Kinds
Use different scales to make different nomographs.
A Nomograph Bulliten Board
Fill the bulliten board with directions, the 3 parallel number lines at
a height convenient for students use.    A string or stick must be available to strentch from -5 on the top to -5 on the bottom with the
string attached at the positive end of the number lines.