Question

EXERCISE TO DO 6.4
1. Find the LCM of the following numbers by using prime factorization method:
(a) 24 and 30
(d) 24, 28 and 30
(b) 36 and 60
(e) 42, 63, and 21
(e) 15 and 20
(1) 60,9 and 75
2. Find the LCM of the following numbers by using division method:
(a) 20 and 56
(d) 60, 75 and 135
(b) 51 and 85
(e) 27, 9 and 36
3 ani
(c) 90 and 100
(f) 36, 48 and 80
3. Find the least number which when increased by 7, is divisible by 12, 15, 13 and 21.
4. Find the least number which when decreased by 9, is divisible by 13,24.80 and 36.
5. Find the least number which when divided by 30, 36, 54 and 63 leaves 3 as
remainder in each case.
6. Three bells in the church toll at intervals of 15,18 and 45 seconds respectively.
After how many seconds will the three bells toll together?
7. Find the least number of five digits which when divided by 72, 96 and 120 leaves
a remainder 7 in each case.
LOTS AROUT HCF AND LCM​

Answer 1

(A) 120
3*2*2*2*5
(B) 15*7*6*2*2=2520
(D) 3*2*2*3*5=180
(E) 3*7*2*3=126
(E) 5*3*4=60