ADDING OF INTEGERS

BY: MS. ABELLA

MAGIC ADDITION

PICK UP THREE DIFFERENT NUMBERS BETWEEN 1 AND 9

EXAMPLE

2 5 7

WRITE THE THREE NUMBERS DOWN NEXT TO THE OTHER , LARGEST FIRST AND SMALLEST LAST.

EXAMPLE:

7 5 2

FORM A NEW THREE-DIGIT NUMBER BY REVERSING THE DIGITS AND WRITE THIS NUMBER UNDERNEATH THE FIRST NUMBER

EXAMPLE;

752

257

NOW, SUBTRACT THE SMALLER THREE-DIGIT NUMBER FROM THE LARGER THREE-DIGIT NUMBER

NOW, LET ME GUESS THE SUM OF THIS 3-DIGIT NUMBER…

IT’S 18!

WHY?

A t ile represents +1

And a tile represents -1

Recall and note that when (+) charge and (-) meets it will explode.

EXAMPLE 1:Use algebra tiles to model

= 5

= -2

EXAMPLE 2: Use algebra tiles to model the sum.

-5+(-2)

- = -7

The same charges will repel to each other

Example 3:

(-2) + (2)

+ =0

There 2 negative charges and two positive charges . These will attract

Rules in adding Integers

• Like signs (+) + (+) or (-) + (-). Find the sum of their absolute values, and use the sign common to both integers

•Unlike signs : (+) + (-) or (-) + (+). Find the difference of their absolute values, and use the sign of the integer with greater absolute value.

Example:

-4 + 5

/-4/ + /5/ = 5 – 4 Find the

= 1 difference of their absolute values

and simplify

Since 5 has the greater value, the sum is positive

Example:

Use a number line to add these integers.

5 + 2

0 2 4 6 8

Begin at 0. Move 5 places to the right , then 2 places more. The stopping place is 7.

Thus, the sum is 7

“The highest form of pure thought is in mathematics”

-Plato

THANK YOU!!!