Subtraction Word Problem

Subtraction Word Problem

A farmer grows 531 tomatoes

and is able to sell 176 of them

in three days.

Given that his supply of tomatoes decreases by 176,

how many tomatoes does he have remaining

at the end of three days?

So he starts with 531 tomatoes

let me give myself a little more space to work with

-- he starts with 531 tomatoes

and he is able to sell 176.

He is essentially going to subtract

the 176 that he is selling.

If we want to figure out

how many he is left with,

we are going to subtract 176.

That‘s how many he sells in three days.

They're asking us:

how many does he have left at the end of three days?

We just have to subtract those 176

from the amount he grew.

It turned into this straight up subtraction problem.

Lets see if we can do it.

If we go straight to the ones place

right over here

and actually let me do it in parallel

because i think that might be interesting over here.

I'm going to do it the way

you traditionally do it here on the left

and then I'm going to show you

what's happening here on the right.

So 531 is the same thing

as 500 + 30 + 1

and if you subtract 176

that is the same thing as subtracting 100

and subtracting another 70 and subtracting another 6

I wrote it this way

because the 5 in 531 is the same thing as 500

The 3 in 531 is in the tens place

so it's really representing 30

the 1 in 531 is in the ones place

so it represents one

and now

it'll be a little bit clearer

what we're doing

when we're borrowing or regouping

on this problem right over here

and so let's start off with the ones place

one is less than 6

It'd be great if we can regoup some of the value

from the rest of the places

so we can go straight to the tens place

the tens place we can borrow

or regroup ten from it

so if we take ten from here

this becomes 20

we're going to take that 10 and add it to the 1

so this will become 11

we just added 10

we moved over 10 from the tens place

to the ones place

if you look at it over here

you could say: Look! we're taking 10 from the 30

that becomes a 20

and then the 1 becomes an 11

the way when I was first in school

people'd say, "You borrow one

from the three"

and you kind of just stick that one right over here

but what you're really doing

is you're taking a 10 from a 30

and making it into a twenty

and you're getting a- you're adding the ten to the one

getting 11

but either way you'll end up with 11

in the ones place

and now you can subtract

11 - 6 is 5

now we go over to the tens place

in the tens place

we now have 2-7

which is really representing 20-70

well we - thats 70 is bigger than the 20

so we want to add some more

to the tens place

well we can go the hundreds place

to find some more value to regroup

so let's see if we can do that

we have 500 here

so what happens when we take a hundred from that

so we're just left with 400 from here

and we take that 100 and we put it in

the tens place

so instead of 20 we now have 120

if you look at it on this problem

since we are using the places here

we're going to take 100 from the 500

and have 400

and then we're going to take that 100

that we took and take it to the tens place

well 100 is 10 tens

so we're going to add 10 to this

so this is going to become a 12

once again, the way-

the kind of more mechanical rope way of thinking about it is that

-oh- you took one away from the four

and you stick that one in front on the two

but you're really taking a 100 from the 500, making it 400

and then adding that 100 to the 20 here

and making it 120

but your writing here is a 12

because it is 12 tens

you're at the tens place

so let me write it down

this is the ones place

this is tens place

and this is the hundreds place

so now that our numbers on top in the tens place

is bigger than the numbers on the bottom

we can subtract

so we get 120-70 that is 50

or 12 minus 7 is 5

5 is in the tens place

so it's really representing 50

let me circle it with the same colour

so you recognise that

this 5 is representing 50

then finally we're in the hundreds place

so 400 -100 is 300

4-1 is 3

but this 3 represents 300

this 5 represents 50

this 5 represents 5

so we're done

we get 355

the farmer is left with 355 tomatoes

at the end of 3 days

or 300+50+5 tomatoes.