model 2 find lcm of numbers Section-Wise Topic Notes With Detailed Explanation And Example Questions

Answer: (c)

∴ 60 = 2 × 2 × 3 × 5

i.e., Numbers = 2, 3, 4 and 5

∴ Required sum = 2 + 3 + 4 + 5 = 14

Answer: (a)

LCM of 16, 18, 20 and 25 = 3600

∴ Required number = 3600K + 4 which is exactly divisible by 7 for certain value of K.

When K = 5,

number = 3600 × 5 + 4

= 18004 which is exactly divisible by 7.

Answer: (c)

LCM of 20, 30 and 40 minutes = 120 minutes

Hence, the bells will toll together again after 2 hours i.e. at 1 p.m.

Answer: (c)

Using Rule 8,

Greatest n digit number which when divided by three numbers P, Q, R leaves no remainder will be

Required Number = (n – digit greatest number) – R

R is the remainder obtained on dividing greatest n digit number by L.C.M of P, Q, R.

LCM of 10, 15 and 20 = 60

Largest 4-digit number = 9999

∴ 166$39/60$ = 9999

∴ Required number = 9999 – 39

= 9960

Answer: (b)

LCM of 21, 36 and 66

∴ LCM = 3 × 2 × 7 × 6 × 11

= 3 × 3 × 2 × 2 × 7 × 11

∴ Required number

= $3^2 × 2^2 × 7^2 × 11^2$

= 213444

Answer: (a)

The LCM of 6, 12 and 18 = 36 = $6^2$