Cogito
Grade 2 Math · Chapter 5 · Lesson 2
Adding Within 1,000
Three columns now, same rule.
10 problems · about 12 minutes · 2.NBT.B.7
What this lesson teaches
The child adds three-digit numbers within 1,000 where no new unit is needed.
- Three digits means three columns.
- Hundreds with hundreds, tens with tens, ones with ones.
- The rule has not changed at all.
Warm-Up Review
From earlier lessons. Loosen up before the new work.
3 problemsReview — Adding and Subtracting Hundreds: 400 + 500 = ?
Answer 900
Why 400 + 500 = 900.
Review — Two-Step Word Problems Within 100: 55 apples. 27 more arrive. 34 are sold. How many are left?
Answer 48
Why 55 + 27 = 82, and 82 − 34 = 48.
Review — Word Problems Within 100: 47 birds. 28 fly away. How many are left?
Answer 19
Why 47 − 28 = 19.
Warm Up
Straightforward practice. Get the method working first.
3 problems341 + 236 = ?
Answer 577
Why 341 + 236 = 577.
What goes with the hundreds?
Answer Other hundreds.
Why Only like units are added together.
215 + 342 = ?
Answer 557
Why 5 hundreds.
Build It Up
The same ideas with more to keep track of.
1 problem406 + 271 = ?
Answer 677
Why No tens in the first number.
Stretch Yourself
Mixed problems. Work out what kind of question it is before you start.
3 problems523 + 154 = ?
Answer 677
Why 6 hundreds, 7 tens, 7 ones.
Two Libraries: One library has 312 books and another has 245. How many books in all?
Answer 557 books
Why 312 + 245 = 557.
The Long Drive: A car drove 421 km, then 253 km more. How far in total?
Answer 674 km
Why 421 + 253 = 674.