Add and Subtract Within 1000 Using the Standard Algorithm

Students apply the standard addition and subtraction algorithms for numbers within 1000, connecting each step of the algorithm to place value understanding. They practice with a variety of problem types, including those requiring multiple regroupings.

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Grade 3 · Addition and Subtraction Within 1000 · question 1 of 3

0 of 12

12 rungs. A star at the top.

− 220 = 12

How it is taught

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Each place is added or subtracted by itself.

Ten in a place makes one of the next place.

Read it: Add and subtract by place

336 + 269: the ones make 15, so 10 of them trade for a ten; the tens make 10, so they trade for a hundred: 605. Subtracting runs the other way: break a ten when a place has too few.

Add by place. 10 of a place trade for 1 of the next.
Subtract by place. Too few in a place? Break 1 from the next place.
Check: 605 − 269 = 336, the number you started with.

Adding and subtracting both work one place at a time.

Adding trades 10 up; subtracting breaks 1 down.

Each undoes the other, so one checks the other.

Line up the places. Add and trade up, or subtract and break down.

Writing 15 in the ones place of 336 + 269.

10 of the 15 ones trade for a ten: 5 ones stay, and the ten joins the tens.

430 − 11 = ___ — 419. 1 one must go, and there are no loose ones at all. Break 1 rod into 10 ones. The same number, grouped differently: 2 rods and 10 ones. Take 11 away: 430 − 11 = 419.

358 + 276

Let's add bigger numbers! Imagine three hundred fifty-eight stickers, and two hundred seventy-six more. How many stickers in all?

We line the numbers up by place value — ones under ones, tens under tens, hundreds under hundreds.

We always start with the ones column. What is eight plus six?

Fourteen! Write the four down in the ones place.

But fourteen also has one ten — so we carry that one up to the tens column.

Now the tens. Add five plus seven, plus the one we carried.

That's thirteen. Write the three in the tens place.

Thirteen tens is one hundred and three tens — carry the one to the hundreds column.

Grade 3 · Adding three-digit numbers with regrouping

Last column. Three plus two, plus the one we carried.

Six. Write the six in the hundreds place.

Three hundred fifty-eight plus two hundred seventy-six is six hundred thirty-four. Nice adding!

What you see

While they climb, your page writes one true line to ask about tonight, and a short note each Sunday.

MayaGrade 3 · Mathematics

Did you know?

A chessboard has 64 squares — share them out between the 8 rows and each row holds exactly 8.

Today’s goal: 1 star — one skill mastered, every rung of its ladder climbed
Climbing now: Divide within 100

An example student.

MayaGrade 3 · Mathematics

Maya earned 2 stars this week — Interpret multiplication as equal groups, which took 6 answers over 3 days before its star landed 3 days ago and Multiply by 6, 7, 8 and 9. Next up: Divide within 100.

An example week.

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Standard

CCSS.3.NBT.A.2

Fluently add and subtract within 1000 using strategies and algorithms based on place value, properties of operations, and/or the relationship between addition and subtraction

Grade 3

Quoted from the Common Core State Standards.

Where this sits

Comes after

Leads to

Add Multi-Digit Whole Numbers Using the Standard Algorithm

What a star here means

A star here is the top of a twelve-rung ladder, in four blocks of equal length — three of facts and one of the skill used in a real question — where a right answer climbs one rung and a wrong one drops back to the start of the block, never below it. The star is kept for good. How we grade

All of Grade 3

This is one rung of 104 in Grade 3 mathematics, in the order they build on each other.

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