## Nomographs for Whole, Fraction, Decimal, and Signed Numbers

 A nomograph is set of 3 equally-spaced parallel number lines and a 4th line or string used to set up and complete an addition or subtraction.     A sheet of blank measured and spaced number line images are provided at the left. Click on the image for a printable page.

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

1. Stretch the rigid line from an added on the top line to the other addend on the bottom line.
2. Read the sum at the intersection of the rigid line and the middle number line.

### To Use a Nomograph to Subtract

1. 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.
2. 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.

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