MathDB
sum of remainders of n divided by 99,132, 229 is n (n>229)

Source: Dutch NMO 2017 p4

September 7, 2019
remainderSumnumber theory

Problem Statement

If we divide the number 1313 by the three numbers 5,75, 7, and 99, then these divisions leave remainders: when dividing by 55 the remainder is 33, when dividing by 77 the remainder is 66, and when dividing by 99 the remainder is 4. If we add these remainders, we obtain 3+6+4=133 + 6 + 4 = 13, the original number. (a) Let nn be a positive integer and let aa and bb be two positive integers smaller than nn. Prove: if you divide nn by aa and bb, then the sum of the two remainders never equals nn. (b) Determine all integers n>229n > 229 having the property that if you divide nn by 99,13299, 132, and 229229, the sum of the three remainders is nn.