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Find-four-positive-integers-each-not-exceeding-70000-and-each-having-more-than-100-divisors-




Question Number 200200 by Fridunatjan08 last updated on 16/Nov/23
Find four positive integers,   each not exceeding 70000 and   each having more than 100   divisors.
Findfourpositiveintegers,eachnotexceeding70000andeachhavingmorethan100divisors.
Answered by mr W last updated on 16/Nov/23
examples:  50400 has 108 divisors  55440 has 120 divisors  60480 has 112 divisors  65520 has 120 divisors  69300 has 108 divisors  ......
examples:50400has108divisors55440has120divisors60480has112divisors65520has120divisors69300has108divisors
Commented by mr W last updated on 17/Nov/23
see also explanation from MM42 sir  in Q#200236
seealsoexplanationfromMM42sirYou can't use 'macro parameter character #' in math mode
Commented by Fridunatjan08 last updated on 16/Nov/23
but how to find these numbers?
buthowtofindthesenumbers?
Commented by mr W last updated on 17/Nov/23
the number can be expressed as  2^a ×3^b ×5^c ×7^d ×11^e ×...  now you select a,b,c,d,e,... such that  2^a ×3^b ×5^c ×7^d ×11^e ×...<70000 and  (a+1)(b+1)(c+1)(d+1)(e+1)...>100  we must “error and try”!
thenumbercanbeexpressedas2a×3b×5c×7d×11e×nowyouselecta,b,c,d,e,suchthat2a×3b×5c×7d×11e×<70000and(a+1)(b+1)(c+1)(d+1)(e+1)>100wemusterrorandtry!

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