CBSE Class 6 Maths Advanced Knowing Our Numbers Very Short Answer Questions Set 02

Very Short Answer Questions

Question 1. Write the Predecessor of 7000 ?
Answer:
Predecessor = 7000 − 1 = 6999.
In simple words: The number just before 7000 is 6999.

Teacher's Note:
1. Predecessor means 1 less.
2. Borrow across the zeros.

Question 2. Which is greater 72389 and 72391 ?
Answer:
Both have 5 digits and the same first three digits 723, so compare the tens digit: 8 and 9.
9 is greater than 8, so 72391 is greater. 72389 < 72391.
In simple words: 72391 is the greater number.

Teacher's Note:
1. Compare from the left; stop at the first different digit.
2. Here the tens digits decide.

Question 3. Arrange the following in ascending order: 2345, 2543, 3452, 4325, 2435
Answer:
Thousands digits: 2345, 2543, 2435 start with 2; 3452 starts with 3; 4325 starts with 4.
Among the numbers starting with 2: 2345 < 2435 < 2543.
Ascending order: 2345, 2435, 2543, 3452, 4325.
In simple words: Smallest first: 2345, 2435, 2543, 3452, 4325.

Teacher's Note:
1. Ascending means from the smallest to the greatest.
2. Sort by the thousands digit, then by the hundreds digit.

Question 4. Write the greatest and the smallest 5 digits numbers by using each of the digits 3, 5, 7, 0, 9 only once ?
Answer:
Greatest: arrange the digits in descending order: 97530.
Smallest: the ascending order is 0, 3, 5, 7, 9, but 0 cannot come first, so put 3 first and then 0, 5, 7, 9: 30579.
In simple words: Greatest 97530 and smallest 30579.

Teacher's Note:
1. The smallest number cannot start with 0.
2. Swap the first two digits of the ascending order when 0 is first.

Question 5. Write the greatest and smallest numbers of 4 digits using all the digits 7, 0, 6 ?
Answer:
There are only three digits, so one digit must be repeated to make a 4-digit number.
Greatest: repeat the greatest digit 7: 7760.
Smallest: 0 cannot lead; keep 6 first and repeat the smallest digit 0: 6007.
In simple words: Greatest 7760 and smallest 6007.

Teacher's Note:
1. For the greatest number repeat the greatest digit; for the smallest repeat the smallest digit.
2. The first digit of the smallest number must still be non-zero.

Question 6. Estimate the 278 × 361 products (by general rule)
Answer:
By the general rule, round each factor to its greatest place: 278 ≈ 300 and 361 ≈ 400.
Estimated product = 300 × 400 = 1,20,000.
In simple words: About 1,20,000.

Teacher's Note:
1. Round each 3-digit factor to the nearest hundred.
2. Multiply 3 × 4 = 12, then add the four zeros.

Question 7. Estimate the following (by rounding off to nearest thousands): (a) 3,456 (b) 7,850
Answer:
(a) The hundreds digit of 3,456 is 4, so round down: 3,000.
(b) The hundreds digit of 7,850 is 8, so round up: 8,000.
In simple words: 3,456 is about 3,000 and 7,850 is about 8,000.

Teacher's Note:
1. Look at the hundreds digit for rounding to thousands.
2. Round up from 5 onwards.

Question 8. Alok and Anuj worked as salesperson at a bookstore. They sold 6283 story books in all. Anuj sold 3324 story books. How many story books were sold by Alok?
Answer:
Alok's books = Total − Anuj's books = 6283 − 3324 = 2959.
In simple words: Alok sold 2959 books.

Teacher's Note:
1. Subtract the part from the whole.
2. Check: 2959 + 3324 = 6283.

Question 9. In an election, the successful candidate registered 4,67,350 votes and his nearest rival secured 2,18,800 votes. By what margin did the successful candidate win the election?
Answer:
Margin = 4,67,350 − 2,18,800 = 2,48,550 votes.
In simple words: He won by 2,48,550 votes.

Teacher's Note:
1. Margin means the difference between the two vote counts.
2. Line up the digits before subtracting.

Question 10. Write in numbers: (a) IX (b) LXV
Answer:
(a) IX = 10 − 1 = 9.
(b) LXV = 50 + 10 + 5 = 65.
In simple words: IX is 9 and LXV is 65.

Teacher's Note:
1. I before X subtracts.
2. L, X, V in order are added.

Question 11. Write in Roman numerals: (a) 12 (b) 34
Answer:
(a) 12 = 10 + 2 = XII.
(b) 34 = 30 + 4 = XXX + IV = XXXIV.
In simple words: 12 is XII and 34 is XXXIV.

Teacher's Note:
1. Split the number into tens and ones.
2. 4 is written IV, not IIII.

Question 12. Subtract the successor of 99 from the predecessor of 201.
Answer:
Successor of 99 = 100.
Predecessor of 201 = 200.
200 − 100 = 100.
In simple words: The answer is 100.

Teacher's Note:
1. Find each number first.
2. Successor adds 1; predecessor subtracts 1.

Question 13. Arrange the following in ascending order: 1345, 87654, 98845, 10034, 2453
Answer:
Four-digit numbers first: 1345 < 2453.
Five-digit numbers: 10034 < 87654 < 98845.
Ascending order: 1345, 2453, 10034, 87654, 98845.
In simple words: Fewer digits means smaller.

Teacher's Note:
1. Compare the number of digits first.
2. Then compare from the left.

Question 14. How many millions make 3 crores ?
Answer:
1 crore = 10 million, so 3 crore = 3 × 10 = 30 million.
Check: 3 crore = 3,00,00,000 = 30,000,000 = 30 million.
In simple words: 3 crore = 30 million.

Teacher's Note:
1. 1 crore = 10 million.
2. Write 3 crore in digits to check.

Question 15. Form the largest and smallest 4-digit number using digits 9, 3, 0, 1.
Answer:
Largest: digits in descending order: 9310.
Smallest: ascending order is 0, 1, 3, 9, but 0 cannot be first, so use 1, 0, 3, 9: 1039.
In simple words: Largest 9310 and smallest 1039.

Teacher's Note:
1. Never start the smallest number with 0.
2. Swap the first two digits of the ascending order.

Question 16. What is the smallest 3-digit number which does not change if digits are written in reverse order.
Answer:
Such a number reads the same both ways (a palindrome), so the hundreds and ones digits are equal.
The smallest 3-digit number is 100, but reversed it is 001, which is different.
Try 101: reversed it is 101. So the answer is 101.
In simple words: 101 reads the same from both sides.

Teacher's Note:
1. Check by reversing the digits.
2. The hundreds digit must equal the ones digit.

Question 17. Out of 180000 tablets of Vitamin A, 18734 are distributed among the students in a district. Find the number of the remaining vitamin tablets.
Answer:
Remaining = 180000 − 18734 = 161266 tablets.
In simple words: 161266 tablets are left.

Teacher's Note:
1. Subtract the distributed tablets from the total.
2. Check: 161266 + 18734 = 180000.

Question 18. Which of the following are meaningless? (a) XD (b) LVV (c) MMMCCXI (d) \( \overline{\mathrm{III}} \)CCS
Answer:
(a) XD is meaningless because X can be subtracted only from L and C, not from D.
(b) LVV is meaningless because V is repeated.
(c) MMMCCXI = 3000 + 200 + 11 = 3211 is a valid numeral.
(d) \( \overline{\mathrm{III}} \)CCS is meaningless because S is not a Roman symbol.
So (a), (b) and (d) are meaningless.
In simple words: Check each numeral against the Roman rules.

Teacher's Note:
1. Look for repeated V, L or D and for wrong subtraction.
2. Only the seven symbols I, V, X, L, C, D, M are allowed.

Question 19. Find the greatest among IV, V, VI and VII.
Answer:
IV = 4, V = 5, VI = 6 and VII = 7.
The greatest is VII.
In simple words: VII (7) is the greatest.

Teacher's Note:
1. Convert each to a number.
2. IV is less than V.

Question 20. Write the sum of XX and XXIX in Roman numerals.
Answer:
XX = 20 and XXIX = 29.
20 + 29 = 49.
49 = 40 + 9 = XL + IX = XLIX.
In simple words: The sum is XLIX.

Teacher's Note:
1. Convert, add and convert back.
2. 40 is XL and 9 is IX.