Question

Difficulty: Very hardDivisibility Rules and Remainder Theorem

A positive integer NN when successively divided by 44, 55, and 66 leaves remainders of 22, 33, and 44, respectively. What is the sum of the remainders obtained when the smallest such number NN is successively divided by 66, 55, and 44, in that order?

Answer: 7

Answer

The sum of the remainders obtained when the smallest such number is successively divided by 6, 5, and 4 is 7.
The smallest positive integer NN satisfying the given successive division conditions is 94. Successively dividing 94 by 6, 5, and 4 yields quotients of 15, 3, and 0 with remainders 4, 0, and 3, respectively. The sum of these remainders is 4+0+3=74 + 0 + 3 = 7.

Step-by-Step Solution

1
Formulate the algebraic equations for successive division and calculate the smallest positive value of NN.
N=94N = 94
By definition of successive division, N=4q1+2N = 4q_1 + 2, q1=5q2+3q_1 = 5q_2 + 3, and q2=6q3+4q_2 = 6q_3 + 4. Setting the non-negative integer quotient q3=0q_3 = 0 yields q2=4q_2 = 4, q1=23q_1 = 23, and N=94N = 94.
2
Perform successive division of 94 by the divisors 6, 5, and 4 in sequence.
The sequence of remainders is 44, 00, and 33.
First stage: 94÷6=1594 \div 6 = 15 remainder 44. Second stage: 15÷5=315 \div 5 = 3 remainder 00. Third stage: 3÷4=03 \div 4 = 0 remainder 33.
3
Calculate the sum of the three remainders.
4+0+3=74 + 0 + 3 = 7
Adding the individual remainders obtained from each stage of the reverse order division.

Key Concept

Successive Division and Remainder Property
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