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) 1,08,737- 47,599 (c) 8325 - 491 (d) 4,89,348 - 48,365

Rounding Numbers is used to ease the calculation by adjusting the digits. We have to round off the values nearest to hundred and tens.

Answer:

a) 439 + 334 + 4317: rounding off to hundred - 5000 and rounding off to tens - 5000

b) 439 + 334 + 4317: rounding off to hundred - 61,100 and rounding off to tens - 61

c) 1,08,737- 47,599: rounding off to hundred - 7,800 and rounding off to tens - 7,840

d) 4,89,348 - 48,365: rounding off to hundred - 4,40,900 and rounding off to tens - 4,40,980

Rounding refers to the process of making a number simpler such that its value remains close to what it was.

Explanation:

(a) 439 + 334 + 4317

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 = 4,300

On adding we get, 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 , 440 + 330 + 4,320 = 5,090

The answer is 5,000 when we round off to the nearest hundreds.

The answer is 5,090 when we round off to the nearest tens.

(b) 1,08,737 - 47,599

Rounding off to hundreds

Rounding off 1,08,734 to the nearest hundreds = 1,08,700

And rounding off 47,599 to the nearest hundreds = 47,600

On subtracting we get, 1,08,700 - 47,600 = 61,100

Rounding off to tens

Rounding off 1,08,734 to the nearest tens = 1,08,730

Rounding off 47,599 to the nearest tens = 47,600

On subtracting we get, 1,08,730 - 47,600 = 61,130

The answer is 61,000 when we round off to the nearest hundreds.

The answer is 61,130 when we round off to the nearest tens.

(c) 8325 – 491

Rounding off to hundreds

Rounding off 8,325 to the nearest hundreds = 8,300

And, rounding off 491 to the nearest hundreds =  500

On subtracting we get, 8,300 - 500 = 7,800

Rounding off to tens

Rounding off 8,325 to the nearest tens = 8,330

And, rounding off 491 to the nearest tens = 490

On subtracting we get, 8,330 - 490 = 7,840

The answer is 7800 when we round off to the nearest hundreds.
The answer is 7840 when we round off to the nearest tens.

(d) 4,89,348 – 48,365

Rounding off to hundreds

Rounding off 4,89,348 to the nearest hundreds = 4,89,300

And, rounding off 48,365 to the nearest hundreds = 48,400

On subtracting we get, 4,89,300 - 48,400 = 4,40,900

Rounding off to tens

Rounding off 4,89,348 to the nearest tens = 4,89,350

Rounding off 48,365 to the nearest tens = 48,370

On subtracting we get, 4,89,350 - 48,370 = 4,40,980

The answer is 4,40,900 when we round off to the nearest hundreds.

The answer is 4,40,980 when we round off to the nearest tens.