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Perfect numbers are numbers where all the factors add to that number. For example 6's factors are 1,2, and 3 and 1+2+3=6. Therefore the next perfect number isn't until 28 which is 1,2, 4, 7, 14 where 1+2+4+7+14= 28
An almost perfect number is a number which, when adding all of its proper divisors (all divisors except himself), gives you one less, or one more then the number itlself. Up to now all known almost perfect numbers are 2^n. So to answer your question, the 2 almost perfect numbers between 5 and 20 are 8 and 16.
Divisors of 8: 1,2,4 -----> 1+2+4=7
Divisors of 16: 1,2,4,8 -----> 1+2+4+8=15
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How many perfect numbers are in between 20 and 50?
The only perfect number between 20 and 50 is 28.
How many perfect square numbers between 1 to 1000 are?
There are 31 perfect square numbers between 1 and 1000 (including 1).
How many odd numbers are between 20 and 158?
There are 69 odd numbers between 20 and 158.
How many perfect squares are there between 20 and 150?
To find the perfect squares between 20 and 150, we need to determine the perfect squares less than 20 and the perfect squares greater than 150. The perfect squares less than 20 are 1, 4, 9, and 16. The perfect squares greater than 150 are 169 and 196. Therefore, there are 5 perfect squares between 20 and 150: 25, 36, 49, 64, and 81.
What are 4 perfect square numbers between 20 and 70?
25, 36, 49, 64
