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Signs

The signs (+ , -) assist in determining and defining the value of a number.

Explanation of adding numbers with signs

Same sign in addition:

neg. + neg. = neg.
-7 + (-3)  =  -10

pos. + pos. = pos.
7 + 3  =  10

                                      otherwise,

                      Different signs, subtract:

                      example:  -7 + (3)  =  ?
1) subtract smaller from larger:  7 - 3  =  4
2) larger number get sign: -7  (neg.)
3) Ans: -7 + (3) = -4

                      example:  -5 + (25) = ?
1) subtract smaller from larger:  25 - 5 = 20
2) larger number get sign: 25  (pos.)
3) Ans: -5 + (25) = +20

EXAMPLES

 8 + 3  =  11

-8 + (-3)   =  -11

8 + (-3)  =  5

 -8 + 3   =  -5

SIGN RULES
Explanation of subtracting number with signs

Change the sign and adding the number

                      example:  7 - (-3)  =  ?
1) change the sign:  7 + 3  =  ?
2) follow addition rule (same sign):

  • pos. + pos. = pos.: 7 + 3 = 10

3) Ans: 7 - (-3) =  10

                      example:  -7 - (-3)  =  ?
1) change the sign:  -7 + 3  =  ?
2) follow addition rule (different signs): 

  • subtract smaller from larger: 7 - 3 =  4

  • larger number get sign: -7  (neg.)

3) Ans: -7 - (-3) = -4
       

                      example:  7 - 3  =  ?
1) change the sign:  7 + (-3)  =  ?

2) follow addition rule (different signs): 

  • subtract smaller from larger: 7 - 3 =  4

  • larger number get sign: 7  (pos.)

3) Ans: 7 - 3 =  4

                      example:  -7 - (3)  =  ?
1) change the sign:  -7 + (3)  =  ?

2) follow addition rule (different signs): 

  • subtract smaller from larger: 7 - 3 =  4

  • larger number get sign: -7  (neg.)

3) Ans: -7 - (3) =  -4

EXAMPLES

9 - 3  =  6

9  - (-3)   =  12

-9  - 3  =  -12

 -9 - (-3)   =  -6

SIGN RULES
Explanation of multiplying numbers with signs

Multiplying Rules:

neg. * neg. = pos.
-7 * (-3)  =  21

pos. *pos. = pos.
7 * 3  =  21

otherwise,

Different signs, always the neg sign

-7 * 3 = -21
 7 * -3 = -21

EXAMPLES

 -6 * (-3)  =  18

-6  * 3   =  -18

6 * - 3  =  -18

 -6 * (-3)   =  18

SIGN RULES
Explanation of dividing numbers with signs

Dividing Rules:

neg. / neg. = pos.
-7 / (-3)  =  2.3333

pos. / pos. = pos.
7 /3  =  2.3333

otherwise,

Different signs, always the neg sign

-7 / 3 = -2.333
 7 / -3 = -2.333

EXAMPLES

9 / (-3)  =  -3

9  / 3   =  3

9 / - 3  =  -3

 -9 / (-3)   =  3

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