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Number Trail Grade 4 / Week 02 / Tuesday
2/6
Week 02 · Add and subtract big numbers

Tuesday

Add bigger numbers
// Place by place, with regrouping
⏱ about 15 min

Tuesday: Add bigger numbers

Lizzy the Lizard is counting seeds for the meadow garden.

Her first sack has 46,875 seeds, and her second has 28,439.

"Can we add numbers this big?" she asks, adjusting her sun hat.

Chris laughs kindly. "The steps are the same, just with more places."

Bennie nods. "And before we start, we can estimate."

"Round each number, add, and you know about how big the sum should be."

Lizzy writes 47,000 + 28,000 in her notebook.

Learn it: the same steps, more places

  46,875
+ 28,439
--------
  75,314

Ones: 5 + 9 = 14. Write 4 and regroup 1 ten.

Tens: 7 + 3 + 1 = 11. Write 1 and regroup 1 hundred.

Hundreds: 8 + 4 + 1 = 13. Write 3 and regroup 1 thousand.

Thousands: 6 + 8 + 1 = 15. Write 5 and regroup 1 ten thousand.

Ten thousands: 4 + 2 + 1 = 7.

So 46,875 + 28,439 = 75,314.

Estimate: 47,000 + 28,000 = 75,000. The sum 75,314 is close, so it makes sense.

ADD THE NUMBERS
  • Read the question.
  • Tap your answer.
46,875 + 28,439 = ?
35,206 + 17,958 = ?
124,530 + 68,275 = ?
509,684 + 276,519 = ?

Learn it: check with an estimate

Round each number to the nearest thousand.

Add the rounded numbers in your head.

If your sum is far from the estimate, check your work.

IS IT REASONABLE?
  • Read the question.
  • Tap your answer.
Lizzy says 46,875 + 28,439 = 65,314. Is that reasonable?
Lizzy says 35,206 + 17,958 = 53,164. Is that reasonable?
Lizzy says 61,094 + 29,812 = 90,906. Is that reasonable?
SOLVE THE STORY
  • Read the question.
  • Tap your answer.
The pond trail had 12,480 visitors in spring and 9,765 in summer. How many in all?
Bees visited 258,300 flowers in May and 147,950 in June. How many visits?
Lizzy plants 7,895 seeds. Then she plants 4,306 more. How many seeds now?
ORDER THE SUMS FROM LEAST TO GREATEST
  • Find or estimate each sum.
  • Tap them from least to greatest.
11st
22nd
33rd
44th
SentenceTrue or false?
46,875 + 28,439 = 75,314?
35,206 + 17,958 = 52,164?
124,530 + 68,275 = 192,805?
WHY THIS EXERCISE35,206 + 17,958 is 53,164.
Try it
Find two big numbers in a book or on a map.
Round each one and estimate their sum.
Then add them in a column.
Is your sum close to your estimate?
Write 46,875 + 28,439 in a column and show the regroups.

Super work with big sums! Tomorrow we subtract.

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