hello my name is Kylie and welcome to subtracting negative numbers in this
video you'll learn how to subtract negative numbers using a number line
ready to hop around on the number line let's go before you watch this video it
may be a good idea to have watched our video adding negative numbers that way
how we use the number line in this video may make better sense before we start
let's review how to write negative integers a negative integer is any
number less than zero remember whole numbers or integers are numbers without
fractions or decimals by the way zero is neutral and is neither positive nor
negative when we write negative numbers we must always use a negative sign to
the left of the number like this both of these show negative 2 when writing
negative numbers in math sentences like addition equations we also use
parentheses to make sure we don't confuse a negative number with
subtraction let's subtract some negative integers we can use the number line to
subtract negative integers very much like using a map to know where we are
where we need to go and where our destination is when taking a trip look
at this number line okay it shows us how integer is moving to the right increase
or go up in value and how integer is moving to the left decrease or go down
in value we will always start at zero we can use this knowledge to help us
subtract negative numbers let's get started with this ordinary math
subtraction sentence 6-4 you've probably seen and calculated a lot of math
sentences just like this very one step one you start at zero as always step two
up six to the right then step three countdown left four because subtracting
means move to the left you land on two and that is your answer 6 minus 4 is 2
now get into subtracting negative numbers remember one very important idea
subtracting a number normally means moving to the left on the number line
but when the number that you're subtracting is negative then the
direction changes again and you end up moving to the right some kids find the
phrase helpful minus times minus equals plus this means if you are dealing with
two minus signs next to each other they cancel each other out and become a plus
this is the same in real-world sentences you can say I do not not like ice cream
this is just a cumbersome way of saying I do like ice cream so the two negatives
turn positive again this is the rule we will use to help us master subtracting
negative integers here is what I mean by this let's start with a positive integer
and subtract a negative integer here we have 3 minus 7 subtraction means moving
to the left but here we are subtracting a negative 7 so we end up moving to the
right 3 minus negative 7 step 1 rewrite the problem to show adding the
positive number instead of subtracting the negative 1
rewrite 3 minus negative 7 as an addition problem 3 plus 7 step 2 to
solve using a number line we always start at zero count up 3 then
count up another 7 of course you will always add this one in your head 3 plus
7 equals 10 step 3 you can then write the original sentence with the correct
answer like this 3 minus negative 7 equals 10
here is a subtraction problem with two negative integers negative 8 minus
negative 3 to calculate or solve this math sentence use the steps we've
learned subtract negative integers step 1 add
the opposite of negative 3 by rewriting the equation as an addition sentence
negative 8 plus 3 step 2 use the number line by starting at 0 step 3 count to
the left 8 spaces for the negative 8 step 4
then add 3 by moving up 3 spaces to the right you land on negative 5 negative 8
plus 3 equals negative 5 step 5 then you can write the original
sentence with the correct answer like this negative 8 minus negative 3 equals
negative 5 let's try one more negative 7 minus negative 10 take the original
subtraction sentence rewrite it by changing it to an addition sentence and
changing the sign of the 10 to a positive 10 remember we do not need to
put a plus sign in front of a positive integer but it does help it should look
like this negative 7 plus 10 then solve it by using the number line like before
you should end up on the positive 3 I know you're brave and can try to on your
own pause the video and try the following practice problems a and B when
you're ready press play and I'll share the answer with you problem a 4 minus
negative 3 problem B negative 5 minus negative 6
how did you do did you remember to switch signs and add instead here are
the answers problem a 4 + + 3 equals 7 problem B negative 5 plus positive 6
equals 1 you can always go back and review the steps if you need more help
you've now tackled subtracting negative numbers I encourage you if you can to
share your special secret to help others do the same
now you will never feel negatively about negative integers it's always a great
idea to keep practicing all your math skills using our fun online games and
quizzes until next time always be positively clever