Maths Class 6th Test from Chapter 3 – Playing With Numbers
M.M: 73 marks Dated: 17/07/2011
Time: 1 hour 45 minutes
Q 1: Fill in the blanks with the right answer (1 mark per question x 32 = 32 marks)
- Divisors of a number are also called its ______________.
- On dividing 7 with 10, the quotient being a whole number is ____ and the remainder is ______.
- The divisors of a number are always ______ or _______ to the number.
- _____ is a factor of every number.
- Every number is a factor of _________.
- The numbers of multiples of any number are ____________.
- The numbers of factors of a given number are ___________.
- Every ______ of a number is an exact divisor of that number.
- Numbers having more than _____ factors are called composite numbers.
- The numbers other than 1 whose only factors are 1 and the number itself are called _________ numbers.
- A number for which sum of all its factors is equal to twice the number is called a __________ number.
- An easier method for finding prime numbers from 1 to 100 without actually calculating factors was given by Greek mathematician _____________.
- ______ is neither prime nor composite number.
- All the factors of 2 are called ___________ numbers.
- A number with 0, 2, 4, 6, 8….. at the __________ place is an even number.
- _____ is the smallest prime number which is even.
- If a number is divisible by ____ and ____ then it is divisible by 6 also.
- The smallest composite number is _____.
- Two prime numbers whose difference is 2 are called _______ __________.
- Three odd prime numbers whose sum is 61 are ____, _____ and _____.
- A number which has either _____ or ____ in its ones place is divisible by 5.
- If a number has 0 in the ones place then it is divisible by ____.
- If the difference between sum of digits at odd places (from the right) and the sum of digits at even places (from the right) is either 0 or divisible by 11, then the number is divisible by _____.
- A number with 3 or more digits is divisible by ____ if the number formed by its last two digits is divisible by 4.
- If the sum of the digits of a number is divisible by ___, then the number itself is divisible by 9.
- Fill in the blank with the number so that it is divisible by 11: 10__01.
- Two numbers having only 1 as a common factor are called ___________ numbers.
- The first common multiple of 3, 8 is ______.
- HCF is also known as _______.
- LCM of 24 and 90 is _______.
- The LCM of two or more numbers is the smallest or least or lowest of their common ___________.
- The HCF of two or more given numbers is the highest of their common _____.
Q 2: Fill the blank with True or False. Also correct the false statement (1 mark per question x 12 = 12 marks)
- If a number exactly divides the sum of two numbers, it must exactly divide the number separately - _________.
- If two numbers are co-primes, at least one of them must be prime - __________
- All numbers which are divisible by 4 must also be divisible by 8 - ___________
- If the sum of digits of a number is a multiple of 3, then the number is divisible by 9 - _________
- The easiest and shortest check to find out if a number is divisible by 2 is to divide it by 2 - __________
- 97 is a prime number - __________
- The number of total factors of 12 are 5 - ________
- 28 is not a perfect number - _________
- 15 is not a composite number - ________
- Every number is a factor but not a multiple of itself - __________
- The sum of two odd numbers and one even number is always odd - _______
- All even numbers are composite numbers - _______
Q 3: Find the smallest 4 digit number which is divisible by 12, 30 and 42. (2 marks)
Q 4: Find the least number which when divided by 8, 12 and 20 leaves remainder 7 in each case. (2 marks)
Q 5: The traffic lights at three different road crossings change after every 36 seconds, 54 seconds and 90 seconds. If they change simultaneously at 8 A.M, at what time will they change simultaneously again? (3 marks)
Q 6: Find LCM of 30, 48, 54. (2 marks)
Q 7: Find HCF of 91, 112, 49. (2 marks)
Q 8: Without actual division by 7 and 9, check the divisibility of 69930 by 7 and 9. Show your method too. (2 marks)
Q 9: Find prime factorisation of 22932. (3 marks)
Q 10: Are two numbers 210, 1573 co-prime? Why or why not? (2 marks)
Q 11: Find common factors of 4, 12, and 30. (2 marks)
Q 12: Find the two common multiples of 3, 5, 10. (2 marks)
Q 13: Write the smallest and greatest digit in the blank space of the given number to make it divisible by 3: 2__7351. (2 marks)
Q 14: Using divisibility test, check if the given number is divisible by 4; by 8; 31795772. Explain your answer. (2 marks)
Q 15: Write six pairs of prime numbers less than 20 whose sum is divisible by 3. (3 marks)
