CBSE MATHEMATICS (IX-X)

Ch Real number basics  *HCF (a,b) =1 , Then a and b are co primes. *Product of primes Theorem of Arithmetic – Composite Number = Product of Primes *HCF and LCM by prime factorization method: HCF = Product of the smallest power of each common factor in the numbers LCM = Product of the greatest power of each prime factor involved in the number *Important Formula  HCF (a,b) X LCM (a,b) =a X b Click here to get the document  Ch 01,02 X Mathematics Question Bank  Click here for solution 

  X th   MATHEMATICS ASSIGNMENT 100424_002 CH.01 REAL NUMBERS   (To prove given number as irrational) Click here to get  same document in pdf form 

  X th   MATHEMATICS ASSIGNMENT 100424_001 CH.01 REAL NUMBERS   (Applications of HCF and LCM) Q.1   Six bells commence tolling together and toll at intervals of 2, 4, 6, 8 10 and 12 seconds respectively. In 30 minutes, how many times do they toll together? (excluding the one at start)     [ ANS: LCM(2,4,6,8,10,12) = 120 sec= 2 min. ,    15 times] Q.2 The traffic lights at three different road crossings change after every 48 sec, 72 sec and 108 sec respectively. If they all change simultaneously at 8:20:00 hrs, when will they again change simultaneously ?                           [ ANS:  LCM=  432 seconds  =  7 min 12 sec .  Hence  answer is 08:27:12 hrs] Q.3 A merchant has 120 ltrs of and 180 ltrs of two kinds of oil. He wants the sell oil by filling the two kinds of oil in tins of equal volumes. What is the greatest of such a tin.   [ ANS: HCF =60 ltrs.] Q.4 Find the least number of soldiers in a regiment such that they stand in rows of 15, 20, 25 and form a p