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Problem on Positive Integer | AIME I, 1995 | Question 6

Try this beautiful problem from the American Invitational Mathematics Examination I, AIME I, 1999 based on Squares and Triangles.

Try this beautiful problem from the American Invitational Mathematics Examination I, AIME I, 1995 based on Problem on Positive Integer.

Problem on Positive Integer – AIME I, 1995

Let $n=2^{31}3^{19}$,find number of positive integer divisors of $n^{2}$ are less than n but do not divide n.

• is 107
• is 589
• is 840
• cannot be determined from the given information

Key Concepts

Integers

Divisibility

Number of divisors

AIME I, 1995, Question 6

Elementary Number Theory by David Burton

Try with Hints

Let $n=p_1^{k_1}p_2^{k_2}$ for some prime $p_1,p_2$. The factors less than n of $n^{2}$

=$\frac{(2k_1+1)(2k_2+1)-1}{2}$=$2k_1k_2+k_1+k_2$

The number of factors of n less than n=$(k_1+1)(k_2+1)-1$

=$k_1k_2+k_1+k_2$

Required number of factors =($2k_1k_2+k_1+k_2$)-($k_1k_2+k_1+k_2$)

=$k_1k_2$

=$19 \times 31$

=589.