Knowing Our Numberss-Solutions Ex-1.3

CBSE Class –VI Mathematics
NCERT 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

(d) 28,292 – 21,496

Answer: (a) 730 + 998

By rounding off to nearest hundreds, 730 rounds off to 700 and 998 rounds off to 1000

Estimated sum = 700 + 1000 = 1700

(b) 796 - 314

By rounding off to nearest hundreds, 796 rounds off to 800 and 314 rounds off to 300

Estimated difference = 800 - 300 = 500

By rounding off to nearest thousands, 12904 rounds off to 13000 and 2888 rounds off to 3000

Estimated sum = 13000 + 3000 = 16000

(d) 28,292 - 21,496

By rounding off to nearest thousands, 28292 rounds off to 28000 and 21496 rounds off to 21000

Estimated difference= 28000 - 21000 = 7000

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 + 4317

(b) 1,08,734 – 47,599

(d) 4,89,348 – 48,365

Answer: (a) 439 + 334 + 4317

Rounding off to nearest hundreds 439, 334 and 4317 may be rounded off to 400, 300 and 4300 respectively.

Estimated sum = 400 + 300 + 4300 = 5000

Rounding off to nearest tens, 439, 334 and 4317 may be rounded off to 440, 330 and 4320 respectively.

Estimated sum = 440 + 330 + 4320 = 5090

(b) 1,08,734 – 47,599

Rounding off to nearest hundreds 1,08,734 and 47,559 may be rounded off to 1,08,700 and 47,600 respectively.

Estimated difference = 1,08,700 - 47,600 = 61100

Rounding off to nearest tens 1,08,734 and 47,559 may be rounded off to 1,08,730 and 47,600 respectively.

Estimated difference = 1,08,730 - 47,600 = 61130

Rounding off to nearest hundreds 8325 and 491 may be rounded off to 8300 and 500 respectively.

Estimated difference = 8300 - 500 = 7800

Rounding off to nearest tens 8325 and 491 may be rounded off to 8330 and 490 respectively.

Estimated difference = 8330 - 490 = 7840

(d) 4,89,348 – 48,365

Rounding off to nearest hundreds 4,89,348 and 48,365 may be rounded off to 4,89,300 and 48,400 respectively.

Estimated difference = 489300 - 448400 = 440900

Rounding off to nearest tens 4,89,348 and 48,365 may be rounded off to 4,89,350 and 48,370 respectively.

Estimated difference = 489350 - 48370 = 440980

Question 3. Estimate the following products using general rule:

(a) 578 x 161

(b) 5281 x 3491

(d) 9250 x 29

Answer: (a) 578 x 161

Rounding off by general rule, 578 and 161 may be rounded off to 600 and 200 respectively

The estimated product = 600 x 200 = 1,20,000

(b) 5281 x 3491

Rounding off by general rule, 5281 and 3491 may be rounded off to 5300 and 3500 respectively

The estimated product = 5,300 x 3,500 = 1,85,50,000

Rounding off by general rule, 1291 and 592 may be rounded off to 1300 and 600 respectively

The estimated product = 1300 x 600 = 7,80,000

(d) 9250 x 29

Rounding off by general rule, 9250 and 29 may be rounded off to 9300 and 30 respectively

The estimated product = 9,300 x 30 = 2,79,000

2,79,000 may be rounded off to 3,00,000