All possible two factors products are formed from numbers 1, 2, 3, 4,…,200. The number of factors out of the total obtained which are multiples of 5, is

Question

Dr. Abubacker · Accepted Answer

(b)
The total number of two factors product$= \ ^{n + 2}C_{8}$. The number of numbers from 1 to 200 which are not multiples of 5 is 160. Therefore, total number of two factors product, which are not multiple of 5, is $\ ^{160}C_{2}$
Hence, required number of factors$= \ ^{200}C_{2} - \ ^{160}C_{2}$
$= 19900 - 12720$
$= 7180$

Q. All possible two factors products are formed from numbers 1, 2, 3, 4,…,200. The number of factors out of the total obtained which are multiples of 5, is

Explanation

Reviewed by Dr. Abubacker

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