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Number Trail Grade 4 / Week 02 / Wednesday
3/6
Week 02 · Add and subtract big numbers

Wednesday

Subtract, place by place
// Place by place, with regrouping
⏱ about 15 min

Wednesday: Subtract, place by place

Samantha the Squirrel gathered 7,352 acorns this fall.

She gave 2,816 acorns to her neighbors for the winter.

"How many do I have left?" she asks, hopping from branch to branch.

Chris writes the numbers one under the other.

"The ones are a puzzle," he says. "Two take away six?"

Bennie smiles. "When the top digit is too small, we regroup."

"We trade one ten for ten ones. Then we have enough."

Learn it: regroup to subtract

  7,352
- 2,816
-------
  4,536

Ones: 2 is less than 6, so regroup 1 ten as 10 ones. 12 - 6 = 6.

Tens: the 5 is now 4. 4 - 1 = 3.

Hundreds: 3 is less than 8, so regroup 1 thousand as 10 hundreds. 13 - 8 = 5.

Thousands: the 7 is now 6. 6 - 2 = 4.

So 7,352 - 2,816 = 4,536.

SUBTRACT THE NUMBERS
  • Read the question.
  • Tap your answer.
7,352 - 2,816 = ?
9,465 - 3,721 = ?
6,184 - 2,957 = ?
8,530 - 4,265 = ?

Learn it: check by adding

Subtraction and addition undo each other.

If 7,352 - 2,816 = 4,536, then 4,536 + 2,816 should equal 7,352.

Check: 4,536 + 2,816 = 7,352. It matches!

CHECK WITH ADDITION
  • Read the question.
  • Tap your answer.
Which sum checks 9,465 - 3,721 = 5,744?
? + 2,957 = 6,184
8,530 - ? = 4,265
Which place do you regroup from when ones are too small?
BIGGER NUMBERS
  • Read the question.
  • Tap your answer.
64,809 - 27,536 = ?
352,741 - 128,396 = ?
90,875 - 45,632 = ?
HOW BENNIE SUBTRACTS
  • Think about how Bennie subtracts.
  • Tap the steps in order.
1First
2Next
3Then
4Last
SentenceTrue or false?
7,352 - 2,816 = 4,536?
6,184 - 2,957 = 4,833?
9,465 - 3,721 = 5,744?
WHY THIS EXERCISE6,184 - 2,957 is 3,227. Each top digit must be big enough before you subtract.
Try it
Pour a handful of dry beans on a plate.
Group them in tens and count them.
Take away 17 beans. Did you need to break open a ten?
Write 7,352 - 2,816 in a column and show each regroup.

Nice subtracting! Tomorrow Chris tells a trail story.

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