Answer:
20 and 4200
Explanation:
Express the numbers as products of their prime factors.
120 = 2 × 2 × 2 × 3 × 5
140 = 2 × 2 × 5 × 7
Identify the prime factors that both numbers have in common and multiply them.
both have 2, 2 and 5, thus
HCF = 2 × 2 × 5 = 20
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Multiply each factor the greatest number of times it occurs in either number.
2 : 3 times
3 : 1 time
5 : 2 times
7 : 1 time
LCM = 2 × 2 × 2 × 3 × 5 × 5 × 7 = 4200