Number Play — Practice

Q1. In the Class 6 'heights and neighbours' line puzzle, each child says a number. What does that number represent?

• A. The child's own height in centimetres.
• B. The number of taller neighbours standing next to the child.
• C. The total number of children taller than the child in the whole line.
• D. The age difference between the child and the tallest child.

Q2. In Ganita Prakash, a cell in a number table is called a 'supercell' when

• A. The number in it is even.
• B. The number in it is larger than every adjacent cell.
• C. The number in it is the smallest in its row.
• D. The number in it is a palindrome.

Q3. In any supercell table with all numbers different, will the cell holding the largest number always be a supercell?

• A. Yes, because no neighbouring cell can have a number bigger than it.
• B. No, only the middle cell can be a supercell.
• C. Only when the largest number is even.
• D. Only when the largest number ends in 0.

Q4. How many 3-digit whole numbers are there in our number system?

• A. 100
• B. 899
• C. 900
• D. 999

Q5. What is the digit sum of the number 68?

• A. 12
• B. 13
• C. 14
• D. 15

Q6. Which of the following numbers is a palindrome?

• A. 1234
• B. 1331
• C. 1342
• D. 1430

Q7. When the Kaprekar process is repeated on any 4-digit number with at least two different digits, every chain eventually reaches the same fixed number. What is it?

• A. 1089
• B. 1729
• C. 6174
• D. 9999

Q8. D.R. Kaprekar, who discovered the magic number 6174, worked as

• A. An engineer in Mumbai.
• B. A mathematics teacher in a government school in Devlali, Maharashtra.
• C. A university professor in Kolkata.
• D. A bank manager in Pune.

Q9. In the Collatz process, what do we do with the current number to get the next?

• A. Add 5 if odd, subtract 5 if even.
• B. Halve it if even; multiply by 3 and add 1 if odd.
• C. Reverse its digits and add the original.
• D. Multiply by 2, then subtract 1.

Q10. Among the whole numbers from 1 to 100, how many times does the digit '7' appear?

• A. 10
• B. 19
• C. 20
• D. 21

Q11. The chapter says we use estimation when

• A. We need the exact number for an official record.
• B. An approximate value is good enough for the purpose at hand.
• C. We are doing multiplication of fractions.
• D. Numbers are too small to count.

Q12. Meghana's birthday 11/02/2011 (dd/mm/yyyy) is special because the digits read the same from left to right and right to left. Such a date is called a

• A. Leap-year date.
• B. Palindromic date.
• C. Repeating date.
• D. Magic date.

Q13. Using the Indian numeral system, where should a comma be placed in the number 60319?

• A. 60,319
• B. 603,19
• C. 6,0319
• D. 6031,9

Q14. 'Game #1' from the Number Play chapter, what is the winning target?

• A. Reach exactly 11 first.
• B. Reach exactly 21 first.
• C. Reach exactly 50 first.
• D. Reach exactly 99 first.

Q15. In the heights-and-neighbours line puzzle, can two children standing next to each other say the same number?

• A. No, the numbers in the line are always different.
• B. Yes, two adjacent children can say the same number depending on the heights.
• C. Yes, but only if both are the tallest children.
• D. No, because every child has exactly two neighbours.