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## Arithmetic

### Unit 18: Lesson 5

Use a number line to add -15 + (-46) + (-29). Created by Sal Khan and Monterey Institute for Technology and Education.

## Want to join the conversation?

• This is probably a really dumb question.. Sigh. Why do some of the numbers, say (-42) have brackets? And how does that effect how the number works in a equation?

@Kitt Hirasaki
So why does, in this video at the start, -15 not have brackets while the others do?
• The first negative number does not have brackets because it is easily recognized as a negative number. The following negative numbers DO have brackets to separate the negative sign on the number from the addition/subtraction operand sign in the question.
Although brackets do mean: "do this first" it doesn't apply here because there are no operations within the brackets.
Aboslute value brackets look like this |x-y| not like this (x-y). Please don't confuse them commenters.
• i dont like subtracting an adding negative number s and im not very good at them what is an easy ways to remember how to add and subtract negative numbers?
same sign add, keep the same sign EX: -3 + -2 = -5
opposite sign subtract, bigger number gets the sign EX: -2 + 6 = 4
• How do you add -32 + 4
• When you add a positive number to a negative number example -32 + 4, then you ignore the negative symbol and change the plus into a minus. 32 - 4=28. Then you add the negative sign at the front to get -28. I hope this helps!
• I think that adding these negative numbers is kinda easy but I still dont understand how to do it.
• Remember these rules
Whenever you find two numbers with same sign add and put corresponding symbol(Common symbol)
*whenever you find nos withot common sign, subract and put greater no.sign.
• if you are adding all negative numbers, can you just add all the numbers together as positives and turn the sum into a negative number?
• Yes, that would work.
• Me seeing the comments from 9 years ago 😀😀😀
• Comments are posted by default with the top ranked ones shown first. If you want to see the more recent comments, change the sort order to "recent".
• Isn't -14+(-46)+(-29) the same as -14-46-29?
• Yes. -14+(-46)+(-29) is the same as -14-46-29.
• what's the effect of parenthesis and is it different than brackets?
• Both parentheses and brackets have the same effect at this stage of math. They both say "Do the stuff inside me first". In my experience, most people use a parenthesis for an initial level of priority and brackets for a secondary level, as in:
3 * [4 + (7 - 3) * (5 / 2)]
= 3 * [4 + (4) * (5/2)]
= 3 * [4 + 10]
= 42
Keep in mind that this is by no means a hard and fast rule, and you're free to use them in whichever order you want, or to only use one or the other since the clarity of the problem isn't too affected.
• Why does multiplying/dividing/subtracting a negative by a negative result in a positive, yet adding a negative by a negative leads to a negative answer?
• When you multiply a negative number to a negative number, they cancel each other out and you are left with a positive number. It's like when you add two positive numbers, they don't cancel each other out, therefore the negative numbers do not cancel each other out. Examples:
23+23= 46
30-10= 20
Now they cancel each other out because you are multiplying them. Examples:
(-5)(-5)= 25
(-2)(-2)=4