Answers to "Knowing our Numbers"

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MATHEMATICS WORKSHEET 2014-15
CLASS VI
KNOWING OUR NUMBERS - Worksheet discussion
1. The smallest 4 digit number using 2,9,6 & 0 is:
a. 6290 b. 2690
c. 0269
d. 2069
2. The difference between place values of 4 in 3,49,406 is:
a. 36000 b. 39600
c. 36900
d. 3600
3. In international system, we write 1 million for
a. 100000
b. 10000
c. 1000000
d. 10000000
4. Write the following numbers in expanded form and write the number names in
Indian and international system of numeration:
a. 523680
b. 34512
c. 100579
d. 3982105
a. 5,23,680 = 5x100000 + 2x10000 + 3x1000 + 6x100+ 8x10
Indian system no. name: five lakhs, twenty three thousand, six hundred eighty.
International system: five hundred twenty three thousand, six hundred eighty
b. 34, 512 = 3x10,000 + 4x1000 + 5x100 + 1x10 +2x1.
Number names:
Indian system: thirty four thousand, five hundred twelve.
International system: thirty four thousand, five hundred twelve
c. 1,00,579 = 1x1,00,000 + 5x100 + 7x10 + 9x1
Number Names:
Indian system: one lakh, five hundred seventy nine.
International system: hundred thousand, five hundred seventy nine.
d. 39,82,105 = 3x10,00,000 + 9x1,00,000 + 8x10,000 + 2x1000 + 1x100 + 5x1.
Indian system: thirty nine lakh, eighty two thousand, hundred five.
International syste,: three million, nine hundred eighty two thousand, hundred
five.
5. Place commas correctly and write the numerals:
a. Fifty six lakhs thirty two thousands and three
56, 32,003
b. Thirty million two hundred and forty three thousand sixty five
30,243,065
c. Eight crore ninety lakhs twenty three thousand five hundred eighty four
8,90,23,584
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d.
Two million nine thousand nineteen
2,009,019.
6. Rewrite using Indian place value system
a. Four hundred five thousand six hundred ten
4,05,610 - Four lakh five thousand six hundred ten
b. Two million five hundred six thousand three hundred fifteen
25,60, 315 - twenty five lakh, sixty thousand, three hundred fifteen
c. Eight million two hundred twenty five thousand five hundred four
82,25,504 - eighty two lakh, twenty five thousand, five hundred four.
7. Round off to nearest tens:
46 - 50
388 - 390
4653 - 4650
46,
388,
4653
8. Round off to nearest hundreds:
894 - 900
3281 - 3300
86543 - 86500
894,
3281, 86543
9. Round off to nearest thousands:
465981 - 466000
5498 - 5000
12965 - 13000
465981,
5498, 12965
10. Estimate the following to the nearest hundred and solve
a. 8042 + 1355
Rounding off: 8000 + 1400 = 9400
b. 5683 + 2146 + 368
Rounding off:
5700 + 2100 + 400 =
c. 7134 - 3658
Rounding off:
7100 - 3700 =
d. 7258 – 2429
Rounding off:
7300 - 2400 =
e. 264 x 147
Rounding off:
300 x 100 =
f. 506 x 179
Rounding off: 500 x 200 = 1,00,000
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g. 472 ÷ 76
Rounding off: 500 ÷ 100 = 5
h. 755 ÷ 120
Rounding off: 800 ÷ 100 = 8
11. Round off 4398 & 256 to the nearest tens. Add them and round off the sum to the
nearest hundred
Rounding off to nearest tens:
4398 -- 4400
256 -- 260
Adding them: 4400 + 260 = 4660
Rounding off the sum to the nearest hundred 4660 -- 4700.
12. Write the following as Hindu-Arabic numerals
a. CLIV = 154
b. XCIV = 94
c. CDXIV= 414
d. DCCLXIX=769
e. CCXXIV = 224
f. MCMXLVIII = 1948
g. LIV = 54
h. MDLXXVII = 1577 i. XLIX = 49
J. DCLX=660
13. Simplify the following:
a.
96 – { (15 ÷ 3) – (45 ÷ 15) } x 10 + 4
Solution: 96 – { (15 ÷ 3) – (45 ÷ 15) } x 10 + 4
= 96 – {(5)-(3)} x 10 + 4
= 96 – 2 x 10 + 4
= 96 - 20 +4 = 96-24 = 72
b.
120 ÷ [ 18 – { 20 - 3 x (9 – 5) } ]
Solution: 120 ÷ [ 18 – { 20 - 3 x (9 – 5) } ]
= 120 ÷ [ 18 –{ 20 - 3 x4 } ]
= 120 ÷ [ 18 –{20-12}]
= 120 ÷ [ 18 –8]
=120 ÷ 10 = 12
c.
120 – [132 ÷ (3 x 4) – { 20 – 15 – 3 } ]
Solution: 120 – [132 ÷ (3 x 4) – { 20 – 15 – 3 } ]
=120 – [132 ÷ (3 x 4) –{5-3}]
=120 – [132 ÷12 - 2]
= 120 – [11-2]
=120 –9 = 111
d.
(19 – 6) x [ 19 + { 15 + 8 – 3 } ]
Solution: (19 – 6) x [ 19 + { 15 + 8 – 3 } ]
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=(19 – 6) x [ 19 + {23-3}]
= 13 x [19 +20] = 13 x 39 = 507
e.
100 – [ 18 – { 16 ÷ 2 – ( 16 – 12 ÷ 3 ) ÷ 2 } ]
Solution: 100 – [ 18 – { 16 ÷ 2 – ( 16 – 12 ÷ 3 ) ÷ 2 } ]
=100 – [ 18 – { 16 ÷ 2 – ( 16 –4) ÷ 2 } ]
=100 – [ 18 – { 16 ÷ 2 –4÷ 2 } ]
=100 – [ 18 – {8 - 2}]
= 100 - [ 18 – 6 ]
=100 - 12 = 88
f.
90 x [ 143 – { ( 6 × 7 ) + ( 110 – 3 x 8 ) } ]
Solution: 90 x [ 143 – { ( 6 × 7 ) + ( 110 – 3 x 8 ) } ]
= 90 x [ 143 – {42 + ( 110 – 24) } ]
= 90 x [ 143 – {42 + 86}]
=90 x [ 143 – 128]
=90 x 15
= 1,350
14 .Give a rough estimate (by rounding off to the nearest hundreds and a closer
estimste (by rounding off to the nearest tens ) and check with the actual.
a) 34768 – 12353
Rough estimate: (rounding off to nearest 100's)
34768 --
34800
12353 -- 12400
34800 - 12400 = 22400.
Closer estimate: (rounding off to nearest 10's)
34768 --
34770
; 12353 -- 12360
34770 - 12360 = 22410
Actual estimate: 34768 – 12353 = 22415.
b) 90156 – 5679 =rough estimate -84500
=closer estimate – 84480
= actual answer - 84477
c) 1023 + 456 + 385 = rough estimate - 2400
=closer estimate - 1870
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= actual answer - 1864
Answer the following
1. How many seven digit numbers are there in all?
Solution:
Smallest 7 digit number = 10,00,000
Biggest 7 digit number = 99, 99, 999
Total number of seven digit numbers = (99,99,999 - 10,00,000) + 1
= 9, 000, 000.
2. How many millions are there in one crore? 10 millions are there in 1 crore.
3. How many thousands make a lakh? 100 thousands.
4. What comes just after 95479999? 95,480,000
5. Write the smallest eight digit number having four different digits. 10,001,123
6. Write all three digit numbers using the digits 1, 3, 5 taking each digit only once and
arrange them in descending order.
135, 315, 513, 531, 153, 351
Descending order: 531, 513, 351, 315, 153, 135
7. Find the difference between the number 1738 and that obtained on reversing its
digits.
Reversing the number: 8371
Difference : 8371 - 1738 = 6633.
8. Find the difference between the place values of two 9s in 7,95,20,986
Difference in Place value: 90,00,000 - 900 = 8,999,100
9. What comes just before 9,900,000 Ans: 9,899,999
10. The difference between 2 numbers is 9476583. If the smaller is 6873547, find the
greater one.
Solution: Difference btween two numbers = 9476583
Smallest no. = 6873547
Another no. = 9,476,583 + 6,873,547 = 16,350,130
11. A number exceeds 3,76,84,955 by 36,15,045. What is that number?
solution: 3,76,84,955 + 36,15,045 = 41,300,000
12. By how much is 7,32,46,510 larger than 4,65,86,422?
7,32,46,510 - 4,65,86,422 = 26,660,088
13. The cost of 16 flats constructed by a builder is ₹ 2,48,09,520. What is the cost of
each flat? ans: 2,48,09,520 ÷ 16 = 1,550,595
14. Mr. Baskar saves ₹ 8756 every month. How much money will he save in 13 years?
Ans: 8756 x 12 x13 = 1,365,936
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15. A textile mill produced 2, 75, 576 m of cloth in a week. Find the daily production of
the mill. Ans: 2, 75, 576 ÷ 7 = 39,368.
___________________________________________________________
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