Title Advanced Series 7th Class Maths - Solutions.pdf ✅

Class 7 – Maths | A - 7 Number System 1 NUMBER SYSTEM Solutions LEVEL -I 1. Correct option: (B) The greatest two-digit number = 99 The smallest two-digit number = 10 ∴The required difference = 99 − 10 = 89. 2. Correct option: (A) The greatest two-digit number = 99 The smallest two-digit number = 10 ∴The required product = 99 × 10 = 990. 3. Correct option: (C) A prime number is a whole number greater than 1 whose only factors are 1 and itself. A factor is a whole number that can be divided evenly into another number. The first few prime numbers are 2, 3, 5, 7, 11, 13, 17, 19, 23 and 29. ∴The required two-digit prime number is primer is 11. 4. Correct option: (B) The total numbers between 1000 and 2000 (including 1000 and 2000) = 1001. Of these, 501 are even numbers and the remaining 500 are odd numbers. ∴The required Number of even numbers between 1000 and 2000 including both is 501. 5. Correct option: (C) The total numbers between 200000 and 600000 (including 200000 and 600000) = 400001. Of these, 400001 are even numbers and the remaining 400000 are odd numbers. ∴The required odd numbers between 200000 and 600000 including both is 4,00,000. 6. Correct option: (A) Since 5321 is the greatest and 1235 is the least number then 5321 − 1235 = 4086. ∴The required number is 4086. 7. Correct option: (C) By trial, we find that the smallest number consists entirely of seven and is exactly divisible by 13 is 777777. On dividing it by thirteen, we get 59829 as the quotient which makes it the smallest number. The given Divisor = 13 and Dividend = 777777 5 9 8 2 9 1 3 7 7 7 7 7 7
Class 7 – Maths | A - 7 Number System 2 6 5 1 2 7 1 1 7 1 0 7 1 0 4 3 7 2 6 1 1 7 1 1 7 0 The Quotient is 59829 and the Remainder is 0. ∴The required number is 59829. 8. Correct option: (B) Composite numbers are only those numbers that have more than two factors. 50, 51, 52, 54, 55, 56, 57, 58, 60, 62, 63, 64, 65, 66, 68, 69, 70, 72, 74, 75, 76, 77, 78, 80, 81,82, 84, 85, 86, 87, 88, 90, 91, 92, 93, 94, 95, 96, 98, 99, 100 are the composite numbers between 50 and 100. Thus, there are total 41 composite numbers between 50 and 100. 9. Correct option: (B) Given that (a+b) and (a-b) are twin primes then ⟹ |a − b − a − b| = 2 ⟹ |−2b| = 2 ⟹ 2b = ±2 ⟹ 2b 2 = ± 2 2 ⟹ b = ±1 ⋅ Since b must be equal to 1 then b is always 1, there can be only one common factor between a and b. Hence a and b are always co-prime. 10. Correct option: (A) Converting the given numbers to like decimals: 0.0005, 0.005, 0.15, 0.175, 0.5, 3.5 = 5 1000 , 50 1000 , 150 1000 , 1750 1000 , 3500 1000 Treating them as whole numbers, the numbers are 5, 50, 150, 1750,3500.