NCERT Solutions Class 6 Maths
Chapter – 1 (Knowing Our Numbers)
The NCERT Solutions in English Language for Class 6 Mathematics Chapter – 1 Knowing Our Numbers Exercise 1.3 has been provided here to help the students in solving the questions from this exercise.
Chapter 1: Knowing Our Numbers
Exercise – 1.3
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.
Solutions:
(a) 730 + 998
Round off to hundreds
730 rounds off to 700
998 rounds off to 1,000
Hence, 730 + 998 = 700 + 1000 = 1700
(b) 796 – 314
Round off to hundreds
796 rounds off to 800
314 rounds off to 300
Hence, 796 – 314 = 800 – 300 = 500
(c) 12,904 + 2,888
Round off to thousands
12,904 rounds off to 13,000
2,888 rounds off to 3,000
Hence, 12,904 + 2,888 = 13,000 + 3,000 = 16,000
(d) 28,292 – 21,496
Round off to thousands
28,292 round off to 28,000
21,496 round off to 21,000
Hence, 28,292 – 21,496 = 28,000 – 21,000 = 7,000
Ten more such examples are
(i) 920 + 120 = 900 + 100 = 1,000
(ii) 2,932 + 8,999 = 3,000 + 9,000 = 12,000
(iii) 4,342 – 3,123 = 4,000 – 3,000 = 1,000
(iv) 529 – 102 = 500 – 100 = 400
(v) 2,989 + 1,890 = 3,000 + 3,000 = 6,000
(vi) 2,998 – 1,012 = 3,000 – 1,000 = 2,00
(vii) 909 – 885 = 900 – 900 = 0
(viii) 6,200 – 3,900 = 6,000 – 4,000 = 2,000
(ix) 8,731 + 1,100 = 9,000 + 1,000 = 10,000
(x) 5,123 – 2,145 = 5,000 – 2,000 = 3,000
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.
Solutions:
(a) 439 + 334 + 4,317
Rounding off to nearest hundreds
439 + 334 + 4,317 = 400 + 300 + 4,300
= 5,000
Rounding off to nearest tens
439 + 334 + 4,317 = 440 + 330 + 4,320
= 5090
(b) 1,08,734 – 47,599
Rounding off to nearest hundreds
1,08,734 – 47,599 = 1,08,700 – 47,600
= 6,11,00
Rounding off to nearest tens
1,08,734 – 47,599 = 1,08,730 – 47,600
= 61,130
(c) 8,325 – 491
Rounding off to nearest hundreds
8,325 – 491 = 8,300 – 500
= 7,800
Rounding off to nearest tens
8,325 – 491 = 8,330 – 490
= 7840
(d) 4,89,348 – 48,365
Rounding off to nearest hundreds
4,89,348 – 48,365 = 4,89,300 – 48,400
= 4,40,900
Rounding off to nearest tens
4,89,348 – 48,365 = 4,89,350 – 48,370
= 4,40,980
Four more examples are as follows
(i) 5,412 + 1,234
Rounding off to nearest hundreds
5,412 + 1,234 = 5,400 + 1,200
= 6,600
Rounding off to nearest tens
5,412 + 1,234 = 5,410 + 1,230
= 6,640
(ii) 822 – 189
Rounding off to nearest hundreds
822 – 189 = 800 – 200
= 600
Rounding off to nearest tens
822 – 189 = 820 – 190
= 630
(iii) 4,567 – 2,345
Rounding off to nearest hundreds
4,567 – 2,345 = 4,500 – 2,300
= 2,200
Rounding off to nearest tens
4,567 – 2,345 = 4,570 – 2,340
= 2,230
(iv) 7,761 + 6,234
Rounding off to nearest hundreds
7,761 + 6,234 = 7,800 + 6,200
= 14,000
Rounding off to nearest tens
7,761 + 6,234 = 7,760 + 6,230
= 13,990
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.
Solutions:
(a) 578 × 161
Rounding off by general rule
578 and 161 rounded off to 600 and 200, respectively
600
× 200
____________
1,20,000
_____________
(b) 5,281 × 3,491
Rounding off by general rule
5,281 and 3,491 rounded off to 5000 and 3500, respectively
5,000
× 3,500
_________
1,75,00,000
_________
(c) 1,291 × 592
Rounding off by general rule
1,291 and 592 rounded off to 1300 and 600, respectively
1,300
× 600
_____________
7,80,000
______________
(d) 9,250 × 29
Rounding off by general rule
9,250 and 29 rounded off to 9000 and 30, respectively
9,000
× 30
_____________
2,70,000
______________
Make four more such examples.
(a) 123 × 89
Rounding off by general rule
123 and 89 rounded off to 100 and 90, respectively
100
× 90
____________
9,000
_____________
(b) 6,123 × 3,123
Rounding off by general rule
6,123 and 3,123 rounded off to 6,000 and 3,000, respectively
6,000
× 3,000
_________
11,80,00,000
_________
(c) 2,381 × 692
Rounding off by general rule
2,381 and 692 rounded off to 2,400 and 700, respectively
2,400
× 700
_____________
16,80,000
______________
(d) 1,251 × 49
Rounding off by general rule
1,251 and 49 rounded off to 1,000 and 50, respectively
1,000
× 50
_____________
50,000
______________
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