1. Try to open my locked suitcase which has the biggest 5 digit odd number as the password comprising the digits 7, 5, 4, 3 and 8. Find the password.
Five digit odd number obtained using 7, 5, 4, 3 and 8 = 87543
(Write in descending order to find the largest number)
2. As per the census of 2001, the population of four states are given below. Arrange the states in ascending and descending order of their population.
| State | Population |
| Tamil Nadu | 72147030 |
| Rajasthan | 68548437 |
| Madhya Pradesh | 72626809 |
| West Bengal | 91276115 |
Ascending order
6,85,48,437 < 7,21,47,030 < 7,26,26,809 < 9,12,76,115
Rajasthan < Tamil Nadu < Madhya Pradesh < West Bengal
Descending order
9,12,76,115 < 7,26,26,809 < 7,21,47,030 < 6,85,48,437
West Bengal > Madhya Pradesh > Tamil Nadu > Rajasthan
3. Study the following table and answer the questions.
| Year | No. of Tigers |
| 1990 | 3500 |
| 2008 | 1400 |
| 2011 | 1706 |
| 2014 | 2226 |
(i) How many tigers were there in 2011?
Ans: 1706
(ii) How many tigers were less in 2008 than in 1990?
difference = Tigers in 1990 – Tigers in 2008
= 3500 – 1400
= 2100
Ans: 2100
(iii) Did the number of tigers increase or decrease between 2011 and 2014? If yes, by how much?
= Tigers in 2014 – Tigers in 2011
= 2226 – 1706
= 520
520 tigers increased from 2011 to 2014
Ans: 520
4. Mullaikodi has 25 bags of apples. In each bag there are 9 apples. She shares them equally amongst her 6 friends. How many apples do each get? Are there any apples left over?
Number of bags = 25
Each bay containing = 9 apples
Total apples = 25 × 9 = 255
225 apples shares 6 friends = 225 ÷ 6
Each of them gets = 37 apples
apples left = 3
Ans: 3 apples left
5. A poultry has produced 15472 eggs and fits 30 eggs in a tray. How many trays do they need?
Total eggs = 15,472
Each tray = 30eggs
Tray needed = 15472 ÷ 30
= 515 Trays
And in one more they fill remaining 22 eggs.
So totally 516 trays needed.
மேற்சிந்தனைக் கணக்குகள்
6. Read the table and answer the following questions.
| Name of the Star | Diameter (in miles) |
| Sun | 864730 |
| Sirius | 1556500 |
| Canopus | 25941900 |
| Alpha Centauri | 1037700 |
| Arcturus | 19888800 |
| Vega | 2594200 |
(i) Write the Canopus star’s diameter in words, in the Indian and the International System.
Indian System
2,59,41,900 – Two Crore Fifty Nine lakh Forty one thousand Nine hundred
International System
25,941,900 – Twenty Five million Nine hundred Forty one thousand Nine hundred
(ii) Write the sum of the place values of 5 in Sirius star’s diameter in the Indian System.
Sirius star’s diameter – 15,56,500
Place values of 5 are 5 – hundred, 5 – Ten thousand, 5 – Lakhs
5,00,000 + 50,000 + 500 = 5,50,500
The sum of place value of 5 = 5,50,500 (Five Lakh fifty thousand five hundred)
Ans: 5,50,500
(iii) Eight hundred sixty four million seven hundred thirty. Write in Indian System.
International System
864,000,730
Indian System
86,40,00,730 – Eight lakh sixty four thousand seven hundred thirty.
(iv) Write the diameter in words of Arcturus star in the International System.
19,888,800 – Nineteen million Eight hundred eighty eight thousand Eight hundred.
(v) Write the difference of the diameters of Canopus and Arcturus stars in the Indian and the International Systems.
Diameter of Canopus – Diameter of Arcturus
25941900 – 19888800 = 6053100
Indian System:
60,53,100 – Sixty Lakhs fifty three thousand one hundred
International System:
6,053,100 – Six million fifty three thousand one hundred.
7. Anbu asks Arivu Selvi to guess a five digit odd number. He gives the following hints.
- The digit in the 1000s place is less than 5
- The digit in the 100s place is greater than 6
- The digit in the 10s place is 8
What is Arivu Selvi answer? Does she give more than one answer
The answer given by Arivuchelvi = 63785, 53781
8. A Music concert is taking place in a stadium. A total of 7,689 chairs are to be put in rows of 90.
Total number of chairs = 7,689
Total Number of rows = 90
Number of rows occupied = 7689 ÷ 90
The remaining chairs = 39
(i) How many rows will there be?
Ans: 85
(ii) Will there be any chairs left over?
Ans: 39
9. Round off the seven digit number 29,75,842 to the nearest lakhs and ten lakhs. Are they the same?
29,75,842 round off nearest lakh = 30,00,000
29,75,842 round off ten lakh = 30,00,000
Yes, they are same.
10. Find the 5 or 6 or 7 digit numbers from a newspaper or a magazine to get a rounded number to the nearest ten thousand.
(i) 14276 – 10000
(ii) 1,86945 – 1,90000