Maths Olympiad Prep

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Number theory Difficulty 3.9 AMC 10/12 Find the answer

Let NN be the least positive integer that is both 2222 percent less than one integer and 1616 percent greater than another integer. Find the remainder when NN is divided by 10001000.

A number or a short expression. Spacing and $ signs are ignored.

Solution

If NN is 2222 percent less than one integer kk, then N=78100k=3950kN=\frac{78}{100}k=\frac{39}{50}k. In addition, NN is 1616 percent greater than another integer mm, so N=116100m=2925mN=\frac{116}{100}m=\frac{29}{25}m. Therefore, kk is divisible by 5050 and mm is divisible by 2525. Setting these two equal, we have 3950k=2925m\frac{39}{50}k=\frac{29}{25}m. Multiplying by 5050 on both sides, we get 39k=58m39k=58m.
The smallest integers kk and mm that satisfy this are k=1450k=1450 and m=975m=975, so N=1131N=1131. The answer is 131\boxed{131}.

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Source: NuminaMath-1.5, licensed Apache-2.0. Statement and solution reproduced as published; topic and difficulty added by this site.