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.


(a) 439 + 334 + 4,317


Rounding off to nearest hundreds,


439 rounds off to 400


334 rounds off to 300


And 4317 rounds off to 4300,


We get,


= 400+300+4300


= 5000


By rounding off to nearest tens,


439 rounds off to 440


334 rounds off to 330


And 4317 rounds off to 4320,


We get,


= 440+330+4320


= 5090


(b) 1,08,734 – 47,599


Rounding off to nearest hundreds,


1, 08,734 rounds off to 1,08,700


47,599 rounds off to 47,600


We get,


= 1, 08,700 – 47,600


= 61100


Rounding off to nearest tens,


1, 08,734 rounds off to 1, 08,730


47,599 rounds off to 47,600


We get,


= 1, 08,730 – 47,600


= 61130


(c) 8325 – 491


Rounding off to nearest hundreds,


8325 rounds off to 8300


491 rounds off to 500


We get,


= 8300 - 500


= 7800


Rounding off to nearest tens,


8325 rounds off to 8330


491 rounds off to 490


We get,


= 8330 – 490


= 7840


(d) 4,89,348 – 48,365


Rounding off to nearest hundreds,


4,89,348 rounds off to 4,89,300


48,365 rounds off to 48,400


We get,


= 489300 – 48400


= 440900


Rounding off to nearest tens,


4,89,348 rounds off to 4,89,350


48,365 rounds off to 48,370


We get,


= 489350 – 48370


= 440980


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