# MP Board Class 6th Maths Solutions Chapter 1 Knowing Our Numbers Ex 1.3

## MP Board Class 6th Maths Solutions Chapter 1 Knowing Our Numbers Ex 1.3

Question 1.
Estimate each of the following using general rule:
(a) 730 + 998
(b) 796 – 314
(c) 12,904 + 2,888
(d) 28,292 – 21,496
Make ten more such examples of addition, subtraction and estimation of their outcome.
Solution:
(a) 730 rounds off to 700
998 rounds off to 1,000
∴ Estimated sum = 700 + 1,000 = 1,700

(b) 796 rounds off to 800 314 rounds off to 300
∴ Estimated difference = 800 – 300 = 500

(c) 12,904 rounds off to 13,000 2,888 rounds off to 3,000
∴ Estimated sum = 13,000 + 3,000 = 16,000

(d) 28,292 rounds off to 28,000
21,496 rounds off to 21,000
∴ Estimated difference = 28,000 – 21,000 = 7,000

Ten more examples:

(i) 540 + 868
540 rounds off to 500
868 rounds off to 900
∴ Estimated sum = 500 + 900 = 1,400

(ii) 1,369 + 215
1, 369 rounds off to 1,000
215 rounds off to 200
∴ Estimated sum = 1,000 + 200 = 1,200

(iii) 46,352 – 11,867
46,352 rounds off to 46,000
11, 867 rounds off to 12,000
∴ Estimated difference = 46,000 – 12,000
= 34,000

(iv) 14,902 + 6,565
14,902 rounds off to 15,000
6,565 rounds off to 7,000
∴ Estimated sum = 15,000 + 7,000 = 22,000

(v) 514 – 386
514 rounds off to 500
386 rounds off to 400
∴ Estimated difference = 500 – 400 = 100

(vi) 27,904 + 69,592
27,904 rounds off to 28,000
69,592 rounds off to 70,000
∴ Estimated sum = 28,000 + 70,000 = 98,000

(vii) 530 – 98
530 rounds off to 500
98 rounds off to 100
∴ Estimated difference = 500 – 100 = 400

(viii) 18,230 – 3,666
18,230 rounds off to 18,000
3,666 rounds off to 4,000
∴ Estimated difference = 18,000 – 4,000 = 14,000

(ix) 56,306 + 17,693
56,306 rounds off to 56,000
17,693 rounds off to 18,000 Estimated sum = 56,000 + 18,000 = 74,000

(x) 4,275 – 125
4,275 rounds off to 4,000
125 rounds off to 100
∴ Estimated difference = 4,000 – 100 = 3,900 Question 2.
Give a rough estimate (by rounding off to nearest hundreds) and also a closer estimate (by rounding off to nearest tens):
(a) 439 + 334 + 4,317
(b) 1,08,734 – 47,599
(c) 8,325 – 491
(d) 4,89,348 – 48,365
Make four more such examples.
Solution:
(a) By rounding off to nearest hundreds, we get
439 rounds off to 400
334 rounds off to 300
4,317 rounds off to 4,300
∴ Estimated sum = 400 + 300 + 4,300 = 5,000
By rounding off to nearest tens, we get
439 rounds off to 440
334 rounds off to 330
4,317 rounds off to 4,320
∴ Estimated sum = 440 + 330 + 4,320 = 5,090

(b) By rounding off to nearest hundreds, we get
1,08,734 rounds off to 1,08,700
47,599 rounds off to 47,600
∴ Estimated difference = 1,08,700 – 47,600 = 61,100
By rounding off to nearest tens, we get 1,08,734 rounds off to 1,08,730
47,599 rounds off to 47,600
∴ Estimated difference = 1,08,730 – 47,600 = 61,130

(c) By rounding off to nearest hundreds, we get
8,325 rounds off to 8,300
491 rounds off to 500
∴ Estimated difference = 8,300 – 500 = 7,800
By rounding off to nearest tens, we get 8,325 rounds off to 8,330
491 rounds off to 490
∴ Estimated difference = 8,330 – 490 = 7,840

(d) By rounding off to nearest hundreds, we get
4,89,348 rounds off to 4,89,300
48,365 rounds off to 48,400
∴ Estimated difference = 4,89,300 – 48,400 = 4,40,900
By rounding off to nearest tens, we get 4,89,348 rounds off to 4,89,350
48,365 rounds off to 48,370
∴ Estimated difference = 4,89,350 – 48,370 = 4,40,980

Four more examples:

(i) 5,235 – 382
By rounding off to nearest hundreds, we get
5,235 rounds off to 5,200
382 rounds off to 400
∴ Estimated difference = 5,200 – 400 = 4,800
Now, by rounding off to nearest tens, we get
5,235 rounds off to 5,240
382 rounds off to 380
∴ Estimated difference = 5,240 – 380 = 4,860

(ii) 7,673+ 436+ 169
By rounding off to nearest hundreds, we get
7,673 rounds off to 7,700
436 rounds off to 400
169 rounds off to 200
∴ Estimated sum = 7,700 + 400 + 200 = 8,300
Now, by rounding off to nearest tens, we get
7,673 rounds off to 7,670
436 rounds off to 440
169 rounds off to 170
∴ Estimated sum = 7,670 + 440 + 170 = 8,280

(iii) 2,05,290 – 17,986
By rounding off to nearest hundreds, we get
2,05,290 rounds off to 2,05,300
17,986 rounds off to 18,000
∴ Estimated difference = 2,05,300 – 18,000 = 1,87,300
By rounding off to nearest tens, we get
2,05,290 rounds off to 2,05,290
17,986 rounds off to 17,990
∴ Estimated difference = 2,05,290 – 17,990 = 1,87,300

(iv) 6,830 + 35,764
By rounding off to nearest hundreds, we get
6,830 rounds off to 6,800
35,764 rounds off to 35,800
∴ Estimated sum = 6,800 + 35,800 = 42,600
Now, by rounding off to nearest tens, we get
6,830 rounds off to 6,830
35,764 rounds off to 35,760
∴ Estimated sum = 6,830 + 35,760 = 42,590 Question 3.
Estimate the following products using general rule:
(a) 578 × 161
(b) 5281 × 3491
(c) 1291 × 592
(d) 9250 × 29
Make four more such examples.
Solution:
(a) 578 × 161
578 rounds off to 600
161 rounds off to 200
∴ The estimated product
= 600 × 200 = 1,20,000

(b) 5281 × 3491
5281 rounds off to 5,000
3491 rounds off to 3,000
∴ The estimated product = 5,000 × 3,000 = 1,50,00,000

(c) 1291 × 592
1291 rounds-off to 1,000 592 rounds off to 600 The estimated product = 1,000 × 600 = 6,00,000

(d) 9250 × 29
9250 rounds off to 9,000 29 rounds off to 30 The estimated product = 9,000 × 30 = 2,70,000 Four more examples:

(i) 3260 × 86
3260 rounds off to 3,000 86 rounds off to 90
∴ Estimated product = 3,000 × 90 = 2,70,000

(ii) 7451 × 4,632
7451 rounds off to 7,000
4632 rounds off to 5,000
∴ Estimated product = 7,000 × 5,000 = 3,50,00,000

(iii) 356 × 204
356 rounds off to 400
204 rounds off to 200
∴ Estimated product = 400 × 200 = 80,000

(iv) 9860 × 692
9860 rounds off to 10,000
692 rounds off to 700
Estimated product = 10,000 × 700 = 70,00,000