Question

Find the HCF and LCM: a) 70, 80, 75 b) 21, 28, 36​
it's urgent fast

Answer 1

solved below,

Step-by-step explanation:

a) 70, 80, 75

LCM= 8, 400

HCF= 5

b) 21, 28, 36​

LCM= 252

HCF= 1

Answer 2

As we know that,

HCF of two or more number if the highest value of number which is common factor of the given numbers.

LCM of two or more number if the lowest value of number which is common multiple of the given numbers.

So, for determining the HCF and LCM we will factorize the given numbers,

So, prime factorization of given number will be,

$70 = 2\times 5 \times 7\\85 = 5 \times 17\\75= 3\times 5 \times 5\\LCM = 5 \times 2 \times 7 \times 17 \times 3 \times 5 = 17850\\HCF = 5 \:(Common\:digit)$

Similarly for second sets of numbers,

$21 = 3\times7\\28 = 2\times2 \times7\\36 = 3 \times 3 \times 2 \times 2\\LCM = 3 \times 7 \times 2 \times 2 \times 3 = 252\\HCF = 1 (As\:no\:number\:Common)$