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Example 19: Shalini walks 785 m to take a bus to school. She travels 2 km 225 m by bus and then
walks 150 m to reach school. Estimate the distance from her home to school.

Solution: Total distance from home to school = 785 m + 2 km 225 m + 150 m
≈ 800 m + 2200 m + 200 m (Rounding off to the nearest hundreds)

≈ 3200 m or 3 km

Practice Time 3F

1. Round off each of the following numbers to the nearest tens.
( a) 898 (b) 1235 (c) 87654

2. Round off each of the following numbers to the nearest hundreds.
( a) 876 (b) 2345 (c) 45673
3. Round off each of the following numbers to the nearest thousands.

( a) 56743 (b) 20980 (c) 30342
4. Write the estimated value of the following numbers in 10s, 100s and 1000s.

Number Estimated value in 10s Estimated value in 100s Estimated value in 1000s
2345

6458
6174

5. Guess the number of times you blink your eyes:
( a) In a minute (b) In an hour (c) In a day
( d) In a week (e) In a month (f) In a year
6. Estimate the number of steps you would take to walk:
( a) From your home to the nearby park

( b) Across the playground from start to end
( c) From your classroom door to the school gate
( d) From your school to the nearest hospital
7. Guess the answer within 30 seconds.
( a) The number of words you use to write an application.
( b) Your heart beats in a minute after running a race.
( c) The number of kidney beans you can hold in your one hand.
( d) The cost of your school shoes.

( e) The number of hours you spend in a month at your school.
8. Estimate the number of words in your math textbook.
9. Estimate the number of students in your school who travel by:
( a) school bus (b) private van (c) on foot
10. Seema took a flight from Delhi to Patna, covering an aerial distance of 861 km, and then from Patna
to Kolkata covering 462 km. Estimate the total distance Seema travelled to reach Kolkata from Delhi,
rounding off to the nearest 100 km.

97 Number Play