Cogito
Grade 4 Math · Chapter 1 · Lesson 6
Subtracting Multi-Digit Numbers
Unbundling across several places.
10 problems · about 15 minutes · 4.NBT.B.4
What this lesson teaches
The child subtracts multi-digit whole numbers fluently, including across zeros.
- Check every column before you start.
- Unbundling can chain across several places.
- Check the answer by adding it back.
Warm-Up Review
From earlier lessons. Loosen up before the new work.
3 problemsReview — Adding Multi-Digit Numbers: 3,758 + 2,496 = ?
Answer 6254
Why 3,758 + 2,496 = 6,254.
Review — Rounding to Any Place: Round 6,349 to the nearest hundred.
Answer 6300
Why 6,349 is just before halfway.
Review — Comparing Large Numbers: Which is bigger, 32,450 or 32,405?
Answer 32450
Why 5 tens beats 0 tens.
Warm Up
Straightforward practice. Get the method working first.
3 problems6,004 − 2,738 = ?
Answer 3266
Why 6,004 − 2,738 = 3,266.
Does unbundling change the number?
Answer No. It is only regrouped.
Why Regrouping rearranges the units without changing the amount.
4,532 − 1,876 = ?
Answer 2656
Why Break at several places.
Build It Up
The same ideas with more to keep track of.
1 problem7,000 − 2,345 = ?
Answer 4655
Why A chain of breaks.
Stretch Yourself
Mixed problems. Work out what kind of question it is before you start.
3 problemsCheck it: 4,655 + 2,345 = ?
Answer 7000
Why It should return 7,000.
The Target: A target of 8,000 has 3,465 done. How many are left?
Answer 4535 left
Why 8,000 − 3,465 = 4,535.
The Collection: A collection of 6,240 loses 1,875. How many are left?
Answer 4365 left
Why 6,240 − 1,875 = 4,365.