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What are the rules for subtracting positive and negative numbers?

Help me! How do you subtract negative numbers?

  • I have been out of school 15 years and now have to take college Algebra. I am doing fine except that for the life of me, I can never get it right when I have to subtract or add with negative numbers. Please explain this to me in simple easy words that a 10 year old can understand. I need to make a cheat sheet that I can refer to when I am working out problems. Please tell me if this is correct and if you have a better or easier way of doing it, please show me. Here's what I got so far: Pos. + Pos. = Pos Neg. + Neg. = Neg Pos + Neg = Subtract the smaller value from the bigger value and keep the sign of the bigger value (example: 14 + (- 21) = - 7 Now Subtracting them is where I have the most trouble.... What are the rules for that, and give a examples. With Multiplying and Diving, I think I am ok... a Pos. x Pos or Pos / Pos. = Pos. and Neg x Neg or Neg / Neg = Pos and a Neg x Pos or Neg / Pos = Neg. Please feel free to make corrections where you see fit. Again I need this explained to me in simple, easy to understand rules so that a 10 year old could understand it. Thank you. I promise to give 10 points to the person who explains it the best. Thank you!

  • Answer:

    you have mostly got it. From yours: Neg. + Neg. = Neg eg. -1 + (-1) = -2 however if it is: -1 - 1 = -2 as well. just to clarify it is like addition but with the negative sign. Good luck

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think of it this way. -1 minus -2, take the - for the minus, and combine that with the - for the negative, and cross them and you get a plus sign. so it would be 1. Need it simpler?

BHurn

you have mostly got it. From yours: Neg. + Neg. = Neg eg. -1 + (-1) = -2 however if it is: -1 - 1 = -2 as well. just to clarify it is like addition but with the negative sign. Good luck

Idris

when subtracting pos to pos or neg. to neg or pos to neg or neg to pos, change the sign of the subtrahend and proceed to addition. if pos change to neg. and if neg change to pos.

Aldrin D

When you subtract a negative, it's like adding. Examples +4 - (-9) = +15 (-5) - (-2) = (-3) Your rules list looks good. Good luck :)

Sarah

-9 - 12 It's called change change Change the first sign to the opposite, then change the subtraction sign to an addition sign 9+12= 21

girlygirl95

Looks like you might be over thinking this... You seem to have the multiplication and division rules down, as well as your addition rules.... If you have to convert all your subtractions into additions...think like this... 5 - 6 = 5 + -6 = -1 <-- In this method you end up falling into one of your addition rules... -5 - -6 = -5 + 6 = 1 <-- In this instance you actually apply your multiplication of negatives to come out with your positive 6 If you want plain rules as above than you end up with this.... Pos - Pos = Subtract the smaller value from the bigger value and keep the sign of the bigger value ex. 10 - 6 = 4 ex. 6 - 10 = -4 Neg - Neg = Subtract the smaller value from the larger value and if the larger is the first value, than it is neg, otherwise it is positive. ex. -10 - -6 = -4 ex. -6 - -10 = 4 pos - neg = Add the values and you get a positive number. ex. 10 - -6 = 16 ex. 6 - -10 = 16 neg - pos = Add the values and you get a negative number ex. -10 - 6 = -16 ex. -6 - 10 = -16 Hopefully this will clear things up a bit

Vladimir F

Looks like you might be over thinking this... You seem to have the multiplication and division rules down, as well as your addition rules.... If you have to convert all your subtractions into additions...think like this... 5 - 6 = 5 + -6 = -1 <-- In this method you end up falling into one of your addition rules... -5 - -6 = -5 + 6 = 1 <-- In this instance you actually apply your multiplication of negatives to come out with your positive 6 If you want plain rules as above than you end up with this.... Pos - Pos = Subtract the smaller value from the bigger value and keep the sign of the bigger value ex. 10 - 6 = 4 ex. 6 - 10 = -4 Neg - Neg = Subtract the smaller value from the larger value and if the larger is the first value, than it is neg, otherwise it is positive. ex. -10 - -6 = -4 ex. -6 - -10 = 4 pos - neg = Add the values and you get a positive number. ex. 10 - -6 = 16 ex. 6 - -10 = 16 neg - pos = Add the values and you get a negative number ex. -10 - 6 = -16 ex. -6 - 10 = -16 Hopefully this will clear things up a bit

Vladimir F

When you subtract a negative, it's like adding. Examples +4 - (-9) = +15 (-5) - (-2) = (-3) Your rules list looks good. Good luck :)

Sarah

-9 - 12 It's called change change Change the first sign to the opposite, then change the subtraction sign to an addition sign 9+12= 21

girlygirl95

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