If a number is divisible by two co-prime numbers,

it is divisible their product

 

Example

80 is divisible by 4 & 5

Since 4 & 5 are co-prime,

80 will be divisible by 4 × 5 = 20 also

Rough

Factors of 4 are 1, 2, 4

Factors of 5 are 1, 5

Since common factor is 1

∴ 4 & 5 are co-prime

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Davneet Singh

Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 14 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.