Worksheet Solution: Rounding off Numbers

Q 1: Round off the following numbers to the nearest 10
1.  77
Ans: 80
Sol: Ones digit is 7 (≥5), so increase the tens digit 7 → 8. Answer = 80.
2. 554
Ans: 550
Sol: Ones digit is 4 (<5), so keep tens digit 5. Answer = 550.
3.  11
Ans: 10
Sol: Ones digit is 1 (<5), so keep tens digit 1. Answer = 10.
4. 440
Ans:  440
Sol: Ones digit is 0, no change. Answer = 440.
5.  99
Ans: 100
Sol: Ones digit is 9 (≥5), so increase tens digit 9 → 10 which becomes 100. Answer = 100.

Q 2: Round of the following numbers to the nearest 100
1.  758
Ans: 800
Sol: Look at the tens digit 5 (≥5), so increase the hundreds digit 7 → 8. Answer = 800.
2. 3,534
Ans: 3 500
Sol: Tens digit is 3 (<5), so keep hundreds digit 5. Answer = 3 500.
3. 67
Ans: 100
Sol: For rounding to nearest 100, treat 67 as 067. Tens digit is 6 (≥5), so increase hundreds digit 0 → 1. Answer = 100.
4. 7,945
Ans: 7 900
Sol: Tens digit is 4 (<5), so keep hundreds digit 9. Answer = 7 900.
5. 45
Ans: 0
Sol: Treat 45 as 045 for hundreds place. Tens digit is 4 (<5), so hundreds digit stays 0. Answer = 0.

Q 3: Round off the following numbers to the nearest 1000
1. 2,364
Ans: 2 000
Sol: Look at the hundreds digit 3 (<5), so keep thousands digit 2. Answer = 2 000.
2. 23,456
Ans: 23 000
Sol: Hundreds digit is 4 (<5), so thousands digit 23 stays. Answer = 23 000.
3. 8,500
Ans: 9 000
Sol: Hundreds digit is 5 (≥5), so increase thousands digit 8 → 9. Answer = 9 000.
4. 77,499
Ans: 77 000
Sol: Hundreds digit is 4 (<5), so keep thousands part 77. Answer = 77 000.
5. 19,739
Ans: 20 000
Sol: Hundreds digit is 7 (≥5), so increase thousands part 19 → 20. Answer = 20 000.

Q 4: Round off the following numbers to the nearest 10 000
1. 63,934
Ans:  ≈ 60 000
Sol: Look at the thousands digit 3 (<5), so keep ten-thousands digit 6. Answer = 60 000.
2. 199,456
Ans: 200 000
Sol: Thousands digit is 9 (≥5), so increase ten-thousands 19 → 20 → 200 000.
3. 8,500
Ans: 10 000
Sol: Ten-thousands place is 0 and thousands digit is 8 (≥5), so increase to 10 000.
4. 77,499
Ans: 80 000
Sol: Thousands digit is 7 (≥5), so increase ten-thousands 7 → 8. Answer = 80 000.
5. 19 739
Ans: 20 000
Sol: Thousands digit is 9 (≥5), so increase ten-thousands 1 → 2. Answer = 20 000.

Q 5: Fill the number marked by the arrow. Draw the arrow to show where the nearest 100 is.
Example:

1. 

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2.  

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3.   

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4.  

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5.  

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Q 6: The questions are based on rounding off the numbers to the nearest ten thousand (10,000), hundred thousand (100,000), one million (1,000,000) and ten million (10,000,000).

Part 1: Round the following numbers to the nearest ten thousand:
1. 63,525
Ans: 60,000
Sol: Thousands digit is 3 (<5), so keep ten-thousands 6. Answer = 60,000.
2.  88,653
Ans: 90,000
Sol: Thousands digit is 8 (≥5), so increase ten-thousands 8 → 9. Answer = 90,000.
3. 77,777
Ans: 80,000
Sol: Thousands digit is 7 (≥5), so increase ten-thousands 7 → 8. Answer = 80,000.
4. 96,875
Ans: 1,00,000
Sol: Thousands digit is 6 (≥5), so increase ten-thousands 9 → 10, which equals 1,00,000.

Part 2:  Round each of the following numbers to the nearest hundred thousand:
1. 546475
Ans: 5,00,000
Sol: Ten-thousands digit is 4 (<5), so keep hundred-thousands 5. Answer = 5,00,000.
2. 384320
Ans: 4,00,000
Sol: Ten-thousands digit is 8 (≥5), so increase hundred-thousands 3 → 4. Answer = 4,00,000.
3. 764300
Ans: 8,00,000
Sol: Ten-thousands digit is 6 (≥5), so increase hundred-thousands 7 → 8. Answer = 8,00,000.
4.  695321
Ans: 7,00,000
Sol: Ten-thousands digit is 9 (≥5), so increase hundred-thousands 6 → 7. Answer = 7,00,000.
5.  356000
Ans: 4,00,000
Sol: Ten-thousands digit is 5 (≥5), so increase hundred-thousands 3 → 4. Answer = 4,00,000.
6.  899549
Ans: 9,00,000
Sol: Ten-thousands digit is 9 (≥5), so increase hundred-thousands 8 → 9. Answer = 9,00,000.

Part 3:  Round each of the following numbers to the nearest one million:
1. 52,08,008
Ans: 50,00,000
Sol: Hundred-thousands part is 2 (<5), so keep the millions digit 50. Answer = 50,00,000.
2. 21,38,520
Ans: 20,00,000
Sol: Hundred-thousands part is 1 (since 38,520 → 38 is <50), the hundred-thousands digit 3 (<5) so keep 20. Answer = 20,00,000.
3. 49,28,619
Ans: 50,00,000
Sol: Hundred-thousands part is 2 (<5), but the ten-thousands/hundred-thousands combined 28,619 has 8 in hundred-thousands place? For one million rounding, look at the hundred-thousands digit (9 in 49 is the ten-million/ millions grouping). Here, the hundreds of thousands part (28) has 2 (<5) - however, standard grouping: number is 4,928,619 → look at hundred-thousands digit 9 (≥5), so increase millions 49 → 50. Answer = 50,00,000.
4. 65,00,000
Ans: 70,00,000
Sol: Hundred-thousands digit is 5 (≥5), so increase millions 6 → 7. Answer = 70,00,000.

Part 4: Round each of the following numbers to the nearest ten million:
1. 21,08,62,013
Ans: 21,00,00,000
Sol: Look at the millions digit part to decide ten-millions. Here, the millions part is 0 (less than 5), so keep ten millions 21. Answer = 21,00,00,000.
2.  46,78,89,250
Ans: 47,00,00,000
Sol: Millions digit block indicates 7 (≥5), so increase ten-millions 46 → 47. Answer = 47,00,00,000.
3. 9,75,94,310
Ans: 10,00,00,000
Sol: Millions block 75 has 7 (≥5), so increase ten-millions 9 → 10. Answer = 10,00,00,000.

Part 5: Round off to the nearest ten million the population of the following states:

1.  California: 31512070
Ans: 30,000,000
Sol: Look at the millions block (1,512,070 → the millions digit 1 is <5 when deciding tens of millions), so keep ten-millions 3. Answer = 30,000,000.
2. New York: 55638318
Ans: 60,000,000
Sol: The millions part indicates 5,563,818 - the millions digit after ten-millions is 5 (≥5), so increase ten-millions 5 → 6. Answer = 60,000,000.