For estimating sums and also differences in the number we use the rounded numbers because that estimations come its nearest tens, hundred, and also thousand.

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Estimating Sums: In plenty of practical calculations, just an approximation is required rather than an exact answer. To do this, numbers are rounded off to a offered place worth of ten, hundred, thousand ... 

Example on Estimating Sums: 1. There room 74 coconut cookies and 48 chocolate cookies in a jar. Calculation the total variety of cookies.

Round the number to the nearest ten and also add.

Rounded to TENS


There are about 120 cookies.

The actual variety of cookies is 122.

The calculation differs from the actual by 2.

2. There are 275 student in class IVth and also 238 student in class Vth. Calculation the total variety of students in the two classes. We can round the numbers one of two people to the nearest ten or the nearest hundreds and add to acquire an estimate. Rounded come TENS


There are approximately 520 students.

The estimate differs from the really by 7. Rounded to HUNDREDS


There are around 500 students. 

The estimate differs indigenous the yes, really by 13. 

Estimating Difference: 

Example ~ above Estimating Difference: The college library has actually 284 science books and also 268 social sciences books.

Estimate the difference in the variety of books. Rounded to TENS


The distinction is about 20 books.

The calculation differs from the really number by 4. Rounded to HUNDREDS


In this case, rounding number to hundreds will certainly not be meaningful as the difference will it is in 0.

Examples top top estimating sums and differences of the numbers:1. The variety of students in great III, IV and also V are 154,129 and 118. Calculation the total number of students in the three classes bring away together.Solution:The rounded numbers are offered to estimate.

So         154     ⇒     200     being much more than 150            129     ⇒     100     being less than 150            118     ⇒     100     being less than 150                              400     So total number as approximated is 400

yes, really number is 401, i beg your pardon is one more than 400>Answer: 400

2. There space 479 girls and also 729 guys in a school. Estimate the total number of students in the school.Solution:For estimation the numbers might be taken to the nearest ten or hundred.

(i)         479     ⇒      480            729     ⇒      730          1208     ⇒     1210 

The estimated number is 1210 i m sorry is 2 an ext than the yes, really number>

(ii)         479     ⇒      500            729      ⇒      700          1208      ⇒     1200 

The approximated number is 1200 i m sorry is 8 much less than the really number>

3. There are 216 pages in the mathematics book of course IV and also 196 pages in the English publication of the same class. Calculation the distinction in the variety of pages the the 2 books.Solution:We use the rounded numbers for estimation.

            216     ⇒      220           - 196     ⇒     200               20     ⇒       20 

The estimated difference in number of pages is 20.The actual difference is additionally 20.

4. Round off the numbers 324 and also 777 come the nearest 10s. Discover the estimated and also actual difference.


Rounding off the number to nearest 10s

324 → 320                           777 → 780

Hence, 780 – 320 = 460 is the approximated difference.

Actual Difference

(i) What is the difference in between the variety of dolls andcars made in a month? provide your answer to nearest 10 and 100.

                                            Dolls                            Cars

          (a) Nearest 10s:    ____________            ____________

          (b) Nearest 100s:  ____________            ____________

(ii) If 1600 super Heroes are offered in the market, then howmany room left for sale?

(iii) how many much more soft toys should be do in the factoryto make the number 7000?


(i) (a) 6730; 5970

    (b) 6700; 6000

(ii) 5242

(iii) 415

III. Round turn off the given numbers come the nearest 10s. Discover theestimated difference and actual difference.

Estimated Difference

Actual Difference

(i) 254 from 875



(ii) 214 native 784



(iii) 657 from 954



(iv) 21 native 287




III. (i) 630, 621

(ii)  570, 570

(iii) 290, 297

(iv)  270, 266

IV. Round turn off the offered numbers to the nearest 100s. Uncover the approximated difference and also actual difference.

See more: How Much Is 15 Meters In Feet And Inches, How Many Feet In 15 Meters

Estimated Difference

Actual Difference

(i) 121 from 145



(ii) 124 from 448



(iii) 215 native 659



(iv) 347 native 728



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4th Grade mathematics ActivitiesFrom Estimating Sums and also Differences to home PAGE

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