Students use data on the world's longest rivers to practice rounding, ordering numbers, and solving addition and subtraction problems.

Let’s solve each question step by step.

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1) Fill in the length of each river to the nearest 100 miles.

To round to the nearest 100, look at the tens digit:
- If it’s 5 or more → round up
- If it’s less than 5 → round down

Amazon: 3976 → tens digit is 7 → round up → 4000
Mississippi: 3902 → tens digit is 0 → round down → 3900
Nile: 4132 → tens digit is 3 → round down → 4100
Ob: 3364 → tens digit is 6 → round up → 3400
Yangtze: 3917 → tens digit is 1 → round down → 3900
Yellow River: 3395 → tens digit is 9 → round up → 3400
Yenisei: 3445 → tens digit is 4 → round down → 3400

✔ Filled table:

| RIVER | LENGTH (miles) | LENGTH TO NEAREST 100 miles |
|---------------|----------------|------------------------------|
| Amazon | 3976 | 4000 |
| Mississippi | 3902 | 3900 |
| Nile | 4132 | 4100 |
| Ob | 3364 | 3400 |
| Yangtze | 3917 | 3900 |
| Yellow River | 3395 | 3400 |
| Yenisei | 3445 | 3400 |

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2) Write the rivers in length order, from smallest to largest below.

List actual lengths:

- Ob: 3364
- Yellow River: 3395
- Yenisei: 3445
- Mississippi: 3902
- Yangtze: 3917
- Amazon: 3976
- Nile: 4132

So from smallest to largest:

Ob, Yellow River, Yenisei, Mississippi, Yangtze, Amazon, Nile

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3) How much longer is the Mississippi than the Ob?

Mississippi = 3902
Ob = 3364
Difference = 3902 - 3364 = 538 miles

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4) How much shorter is the Yellow River than the Nile?

Nile = 4132
Yellow River = 3395
Difference = 4132 - 3395 = 737 miles

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5) What is the total length of the 3 longest rivers?

Longest 3: Nile (4132), Amazon (3976), Yangtze (3917)

Add them:
4132 + 3976 = 8108
8108 + 3917 = 12,025 miles

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6) What is the difference in length between the longest and shortest river?

Longest: Nile = 4132
Shortest: Ob = 3364
Difference = 4132 - 3364 = 768 miles

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7) Which two rivers are closest in length?

Look at differences between nearby rivers:

- Mississippi (3902) and Yangtze (3917): diff = 15
- Amazon (3976) and Yangtze (3917): diff = 59
- Yellow River (3395) and Ob (3364): diff = 31
- Yenisei (3445) and Yellow River (3395): diff = 50

Smallest difference is 15 miles → Mississippi and Yangtze

✔ Answer: Mississippi and Yangtze

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8) Tyger says “The two longest rivers put together are longer than the three shortest rivers put together.” Is he correct?

Two longest: Nile (4132) + Amazon (3976) = 8108

Three shortest: Ob (3364) + Yellow River (3395) + Yenisei (3445)
= 3364 + 3395 = 6759; 6759 + 3445 = 10,204

Compare: 8108 vs 10,204 → 8108 < 10,204

So Tyger is NOT correct.

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9) Circle the correct answer. The total length of all the rivers is about...

Add all 7 rivers:

Amazon: 3976
Mississippi: 3902
Nile: 4132
Ob: 3364
Yangtze: 3917
Yellow River: 3395
Yenisei: 3445

Let’s add step by step:

Start with 3976 + 3902 = 7878
+4132 = 12,010
+3364 = 15,374
+3917 = 19,291
+3395 = 22,686
+3445 = 26,131

Total ≈ 26,131 miles

Closest option: 25,000 miles

(20,000 is too low, 10,000 way too low)

✔ Circle: 25,000 miles

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Final Answer:

1) Rounded lengths:
Amazon: 4000, Mississippi: 3900, Nile: 4100, Ob: 3400, Yangtze: 3900, Yellow River: 3400, Yenisei: 3400

2) Order (smallest to largest):
Ob, Yellow River, Yenisei, Mississippi, Yangtze, Amazon, Nile

3) 538 miles

4) 737 miles

5) 12,025 miles

6) 768 miles

7) Mississippi and Yangtze

8) No, Tyger is not correct.

9) 25,000 miles