Class 7 Maths Chapter 6 Very Short Question Answer - Number Play

Q1: What is the 20th even number in the sequence 2, 4, 6, 8, ...?

Ans: 40
Explanation: The nth even number is 2n. For n = 20, 2 × 20 = 40.

Q2: Meera has 5 boxes and odd number cards (1, 3, 5, ...). Can she pick 5 cards that add to 50?

Ans:No
Explanation: Adding 5 odd numbers always gives an odd sum (each odd number adds an unpaired unit). 
Since 50 is even, it’s impossible.

Q3: Sana adds 6 odd numbers. Is the sum even or odd?

Ans:Even
Explanation: Each odd number has one unpaired unit. 
For 6 odd numbers, the 6 unpaired units pair up (6 ÷ 2 = 3 pairs), so the sum is even.

Q4: Raj has a 14 × 19 grid. Is the number of small squares even or odd?

Ans: Even
Explanation: The number of squares is 14 × 19. 
Since 14 is even and 19 is odd, even × odd = even, 
so the total is even.

Q5: What is the 30th odd number in the sequence 1, 3, 5, ...?

Ans:59
Explanation: The nth odd number is 2n - 1. 
For n = 30, 2 × 30 - 1 = 60 - 1 = 59.

Q6: In a 3 × 3 magic square with numbers 1 to 9, what is the sum of each row?

Ans:15
Explanation: The sum of numbers 1 to 9 is 45. 
In a magic square, each of the 3 rows sums to the same value, 
so 45 ÷ 3 = 15.

Q7: Tara writes the Virahãnka sequence: 1, 2, 3, 5, 8, 13, 21, 34, 55, 89. What is the next number?

Ans:144
Explanation: Each number in the Virahãnka sequence is the sum of the two previous numbers. So, 55 + 89 = 144.

Q8: In the puzzle K + K + K = LK, where K and L are digits, what is K?

Ans: 5
Explanation: 3K = LK (a two-digit number with units digit K). 
So, 3K = 10L + K. (expansion of a two digit number = 10p + q)
Subtract K: 2K = 10L. 
Thus, K = 5L. 
Since K and L are digits, L = 1, K = 5. 
Check: 5 + 5 + 5 = 15, and LK = 15.

Q9: A bulb is ON. Vijay toggles it 63 times. Is the bulb ON or OFF?

Ans: OFF
Explanation: Each toggle switches the bulb (ON to OFF or OFF to ON). 
Starting ON, 63 toggles (odd number) means it ends OFF.

Q10: In the Virahãnka sequence, two numbers are 377 and 610. What is the next number?

Ans: 987
Explanation: In the Virahãnka sequence, the next number is the sum of the two previous ones. 
So, 377 + 610 = 987.