I'm going to be talking about

subtracting three-digit numbers this is

11.7 we can subtract three-digit numbers

by using a work map that shows the place

values and models to help us so we're

going to subtract 425 minus 136 and this

H means hundreds the T means tens and

the o means ones we can keep them in the

correct column we even have a box for

regrouping C so 425 we have four

hundreds we have two tens and we have

five ones don't we we need to take away

136 looking at this what we need to do

is take six from the five but we can't

the five isn't big enough so what we're

going to do is we're going to regroup

the two as a 1 I'm going to give that 10

to the ones place so this is not a 5

anymore it's a 15 15 take away 6 is 9

now we have 1 and we need to take 3 away

but we can't do that so we regroup this

to be a 3 and we give it to the tens

place now we have 11 tens and we need to

take 3 away that's an 8 8 9 10 11

see 8 plus 3 is 11 we can do the

opposite we can do addition to check our

subtraction 3 minus 1 is a 2 so we

should have 289 so let's see how this

works

we had 425 here and we need to take away

not 6 ones right but we can't take away

6 ones because there's only 5 ones there

so what we can do is we can break this

10 up in to ones and regroup it to be

ones C now we can too

six of them away one two three four five

six

we take six of them away and how many

ones are left one two three four five

six seven eight nine just like we got

here we have nine ones now it says that

we had to take we have to take away

three tens but I only see one ten here

so what we can do is we can move our

ones over and out of the way a little

bit we only have one ten here we can

split this hundred up as ten tens see

and regroup it to the tens place now we

have 1 2 3 4 5 6 7 8 9 10 11 10 just

like we got up here we have 11 10s now

we can take three away we can take away

1 2 3 and we're left with 1 2 3 4 5 6 7

8 10 8 tens and 9 ones just like we got

when we did the math now it says we need

to take away a 100 well if I take away a

100 that's one of these big squares what

are we gonna be left with two hundreds

see eight tens and nine eleven it's just

like we got there see so if you need to

use models that's okay and you can use a

work mat like this that has little boxes

for your regrouping all right so let's

see if we can subtract these we have 761

and we need to take away 429 we have 1

and we need to take away 9 we can't

because the 9th so big so let's regroup

from the tens place we'll turn this into

a five and we're gonna give the 10 to

the ones place so now instead of 1 we

have 11 because 10 plus 1 is 11 isn't it

11 minus 9 is a

right five minus two is a three and

seven minus four is a three c-suite to

regroup two times didn't we

but that's okay we can do that we can

regroup many many times if we have to in

a math problem let's try this one

we have 574 and we need to subtract 228

so in the ones place we have a 4 and we

need to take away an 8 and we can't

because the 8 so big so we're going to

turn this into a 6 and regroup our four

ones into 14 ones because we gave that

10 to the ones place 14 take away 8 is

do you know if you said 6 you're right 6

take away 2 is 4 and 5 take away 2 is 3

we have 346 all right let's try this one

we have 604 and we need to subtract 152

we have 4 take away 2 we can do that we

don't need to regroup that's a 2 isn't

it we have 0 take away 5 oh we need to

regroup because that 0 is too small this

becomes a 5 we give that to the tens

place 10 tens make a hundred so we have

10 tens now 10 take away 5 is 5 and 5

take away 1 is 4 we have 450 - all right

let's try it again I'm gonna get lots of

practice we have 450 and we need to

subtract 137 we can't have zero and take

7 away so we're gonna regroup this is

going to become a 4 and we're gonna give

that 10 to the ones place now we have 10

take away 7 we could do that that's a 3

we have 4 take away 3 for the tens place

that's a 1 and we have 4 take away 1

that's a 3 we have 300

13 okay let's try it again

this is gonna be a little bit harder

because we're gonna have to regroup

twice we have 306 - 179 we have a six

and we need to take 9 away and we can't

do that the 9 is too big and we can't

regroup from the tens place because it's

a zero so now we have to go way over to

here that becomes a 2 it's one less and

instead of zero tens now we have ten

tens cuz ten tens make a hundred right

now the ones place can be regrouped and

the tens place can be regrouped because

it has enough doesn't it so this 10 is

going to become a nine and this six is

going to become a 16 we're going to give

that take one of the tens from here and

give it to the ones place 16 minus 9 is

do you know that would be a seven nine

minus seven is a two and two minus one

is one C so there's a zero in the tens

place and you still need to regroup you

just go to the hundreds place and

regroup a couple times see we regrouped

a lot didn't we but that's okay let's

try it again we have eight hundred five

minus three hundred eighty eight we have

a five and we can't take away eight and

there's zero tens so we can't regroup

from the tens place we're gonna have to

keep going and go to the hundreds place

that's gonna become a seven so now

instead of zero tens we have ten tens

because ten tens make 100 that's what we

regrouped from the hundreds place we

took one of the hundreds away and gave

it to the tens as ten tens right now we

can regroup and give some to the ones

place

so the ten is going to become a nine and

we're gonna give it to the ones place so

instead of five ones we have 15 ones 15

take away eight is

do you know we'd be a seven nine

take away eight that's an easy one isn't

it it's a one and seven take away three

is a four we have 417 okay so we had to

regroup a couple times all right it's no

different than regrouping once you're

just doing it again

okay it's not harder it just takes a

little longer okay let's try some

problem-solving it says which two

numbers will make each sum or difference

we have 105 246 218 and 134 we need to

find the difference of 112 that means

because difference is the answer and

subtraction that means that the answer

is 112 and because it's a difference we

know it's going to be a subtraction

problem so we need to find which two of

these numbers are going to equal 112

when you subtract one from the other and

the only way to do it is to try

different combinations see little plus

signs telling us just try different

combinations so we can try 246 minus 105

we could try that 246 minus 105 6 minus

5 is a 1 4 minus 0 is 4 2 minus 1 is 1

well that's 141 that's not a hundred and

12 so that's not the right combination

let's try 246-260 n-- right because we

gave a 10 to the ones place 16 minus 8

well 8 plus 8 16 that's a double so we

know that's an 8 3 minus 1 is a 2 and 2

minus 2 is a 0 hmm that's only 28

so 246 minus 105 didn't work 246 - 218

didn't work let's try 246 minus the 100

it could also be 218 - 105 couldn't it

or 218 - 130 if we could even try half -

we might even have to do that right so

let's try 246 - 134 6 minus 4 is a 2 4

minus 3 is a 1

oh look at this 2 minus 1 is a 1 it is

112 so we know that two numbers are 246

and 134 246 and 134 so the only way we

could figure out which would make the

difference of 112 was by doing math on

the side and just trying different

combinations ok now this one says the

sum of 351 so two of these numbers when

added together because a sum is an

answer in addition isn't it

two of these numbers added together are

gonna give us a sum of 351 we have to

figure out which ones they are

if we add these two together will that

give us 351 if we add these two together

will that do it or will this do it so we

need to try different combinations

let's try 105 and 246 the first two

numbers okay so we have 5 because we're

adding now 5 plus 6 well 5 Plus 5 is 10

so 5 plus 6 is 11 we regroup the 1 and

put the 1 down 1 plus 0 plus 4 is 5 and

1 plus 2 is 3 look at that we got lucky

the very first two numbers we tried

ended up being the right ones it is 351

so we know the answer is the two numbers

that will give us a sum of 351 is 105

and 246 105 + 246 and the only way to

find the answer to this problem was to

do guess and check right we had to keep

trying different combinations until we

got the right answers all right we don't

have to do this

one because we already found the answer

all right okay so that was subtracting

three-digit numbers just remember you

might have to regroup more than once and

it's not harder just takes a little

longer that's all it's just like

regrouping one time so we're gonna move

on to subtracting some three-digit

numbers again in the next video

and we're gonna practice what we've

learned okay we're gonna subtract to get

to digit and one digit numbers from

three digit numbers and we're gonna

subtract three digit numbers from three

digit numbers all right okay I hope I'll

see you there and don't forget to hit

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don't forget that this is a second-grade

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order to help you with your math okay

bye