RS Aggarwal Solutions: Number System (Exercise 1E) | Mathematics (Maths) Class 6 PDF Download

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Q.1. Estimate each of the following products by rounding off each number to the nearest ten.
Q.1. 38 × 63.
Ans. (38 × 63)

38 estimated to the nearest ten = 40

63 estimated to the nearest ten = 60
∴ 40 × 60 = 2400

Q.2. 54 × 47.
Ans. (54 × 47)
54 estimated to the nearest ten = 50
47 estimated to the nearest ten = 50
∴ 50 × 50 = 2500

Q.3. 28 × 63.
Ans. (28 × 63)
28 estimated to the nearest ten = 30
63 estimated to the nearest ten = 60
∴ 30 × 60 = 1800

Q.4. 42 × 75.
Ans. (42 × 75)
42 estimated to the nearest ten = 40
75 estimated to the nearest ten = 80
∴ 40 × 80 = 3200

Q.5. 64 × 58.
Ans. (64 × 58)
64 estimated to the nearest ten = 60
58 estimated to the nearest ten = 60
∴ 60 × 60 = 3600

Q.6. 15 × 34.
Ans. (15 × 34)
15 estimated to the nearest ten = 20
34 estimated to the nearest ten = 30
∴ 20 × 30 = 600

Estimate each of the following products by rounding off each number to the nearest hundred :
Q.7. 376 × 123.
Ans. (376 × 123)
376 estimated to the nearest hundred = 400
123 estimated to the nearest hundred = 100
∴ 400 × 100 = 40000

Q.8. 264 × 147.
Ans. (264 × 147)
264 estimated to the nearest hundred = 300
147 estimated to the nearest hundred = 100
∴ 300 × 100 = 30000

Q. 9. 423 × 158.
Ans. (423 × 158)
423 estimated to the nearest hundred = 400
158 estimated to the nearest hundred = 200
∴ 400 × 200 = 80000

Q.10. 509 × 179.
Ans. (509 × 179)
509 estimated to the nearest hundred = 500
179 estimated to the nearest hundred = 200
∴ 500 × 200 = 100000

Q.11. 392 × 138.
Ans. (392 × 138)
392 estimated to the nearest hundred = 400
138 estimated to the nearest hundred = 100
∴ 400 × 100 = 40000

Q.12. 271 × 339.
Ans. (271 × 339)
271 estimated to the nearest hundred = 300
339 estimated to the nearest hundred = 300
∴ 300 × 300 = 90000

Estimate each of the following products by rounding off the first number upwards and the second number downwards :
Q.13. 183 × 154.
Ans. (183 × 154)
183 is rounded off upwards = 200
154 is rounded off downwards = 100
∴ 200 × 100 = 20000

Q.14. 267 × 146.
Ans. (267 × 146)
267 is rounded off upwards = 300
146 is rounded off downwards = 100
∴ 300 × 100 = 30000

Q.15. 359 × 76.
Ans. (359 × 76)
359 is rounded off upwards = 400
76 is rounded off downwards = 70
∴ 400 × 70 = 28000

Q.16. 472 × 158.
Ans. (472 × 158)
472 is rounded off upwards = 500
158 is rounded off downwards = 100
∴ 500 × 100 = 50000

Q.17. 680 × 164.
Ans. (680 × 164)
680 is rounded off upwards = 700
164 is rounded off downwards = 100
∴ 700 × 100 = 70000

Q.18. 255 × 350.
Ans. (255 × 350)

255 is rounded off upwards = 300
350 is rounded off downwards = 300
∴ 300 × 300 = 90000

Estimate each of the following products by rounding off the first number downwards and the second number upwards :
Q.19. 356 × 278.
Ans. (356 × 278)
356 is rounded off downwards = 300
278 is rounded off upwards = 300
∴ 300 × 300 = 90000

Q.20. 472 × 76.
Ans. (472 × 76)
472 is rounded off downwards = 400
76 is rounded off upwards = 80
∴ 400 × 80 = 32000

Q.21. 578 × 369.
Ans. (578 × 369)
578 is rounded off downwards = 500
369 is rounded off upwards = 400
∴ 500 × 400 = 200000