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) $8325 – 491$
(d) $4,89,348 – 48,365$
Make four more such examples.

Given:

(a) $439 + 334 + 4,317$

(b) $1,08,734 – 47,599$

(c) $8325 – 491$

(d) $4,89,348 – 48,365$

To do:

We have to give a rough estimate (by rounding off to nearest hundreds) and also a closer estimate (by rounding off to nearest tens)

Solution:

(a) Rounding off to hundreds

Rounding off $439$ to the nearest hundreds$=400$

Rounding off $334$ to the nearest hundreds$=300$

Rounding off $4,317$ to the nearest hundreds, we get $4,300$

On adding we get,

$\boxed{400+300+4,300=5,000}$

Rounding off to tens

Rounding off $439$ to the nearest tens$=440$

Rounding off $334$ to the nearest tens$=330$

And, rounding off $4,317$ to the nearest tens$=4,320$

On adding we get

$\boxed{440+330+4,320=5,090}$

(b) Rounding off to hundreds

Rounding off $108734$ to the nearest hundreds$=108700$

Rounding off $47599$ to the nearest hundreds$=47600$

On subtracting we get,

$\boxed{108700-47600=61100}$

Rounding off to tens

Rounding off $108734$ to the nearest tens$=108730$

Rounding off $47599$ to the nearest tens$=47600$

On subtracting, we get

$\boxed{108730-47600=61130}$

(c) Rounding off to hundreds

Rounding off $8325$ to the nearest hundreds$=8300$

Rounding off $491$ to the nearest hundreds$=500$

On subtracting we get,

$\boxed{8300-500=7800}$

Rounding off to tens

Rounding off $8325$ to the nearest tens$=8330$

Rounding off $491$ to the nearest tens$=490$

On subtracting, we get

$\boxed{8330-490=7840}$

(d) Rounding off to hundreds

Rounding off $489348$ to the nearest hundreds$=489300$

Rounding off $48365$ to the nearest hundreds$=48400$

On subtracting we get,

$\boxed{489300-48400=440900}$

Rounding off to tens

Rounding off $489348$ to the nearest tens$=489350$

Rounding off $48365$ to the nearest tens$=48370$

On subtracting, we get

$\boxed{489350-48370=440980}$

 Four more examples are as follows

(i) $4682 + 523$

Rounding off to nearest hundreds

$4682 + 523 = 4700 + 500$

$= 5200$

Rounding off to nearest tens

$4682 + 523 = 4680 + 520$

$= 5200$

(ii) $5358 + 463$

Rounding off to nearest hundreds

$5358 + 463 = 5400 + 500$

$= 5900$

Rounding off to nearest tens

$5358 + 463 = 5360 + 460$

$= 5800$

(iii) $678 + 5462$

Rounding off to nearest hundreds

$678 + 5462 = 700 + 5500$

$= 6200$

Rounding off to nearest tens

$678 + 5462 = 680 + 5460$

$= 6140$

(iv) $1632 + 1475$

Rounding off to nearest hundreds

$1632 + 1475 = 1600 + 1500$

$= 3100$

Rounding off to nearest tens

$1632 + 1475 = 1630 + 1480$

$= 3110$