Maths Olympiad Prep

Track / Stage 4 / 220 of 340 #480 of 1964

Problem 480

AMC 12 late, AIME early
Combinatorics Difficulty 4.9 Find the answer

2. Let the set M={1,99,1,0,25,36,91,19,2,11}M=\{1,99,-1,0,25,-36,-91,19,-2,11\}, and denote all non-empty subsets of MM as Mi,i=1,2,M_{i}, i=1,2, \cdots, 2013. The product of all elements in each MiM_{i} is mim_{i}. Then i=12013mi=\sum_{i=1}^{2013} m_{i}= \qquad .

A number or a short expression. Spacing, $ signs and \frac vs / are all fine.

Official solution

i=12013mi=(1+1)(1+99)(11)(1+0)(1+11)1=1 \sum_{i=1}^{2013} m_{i}=(1+1)(1+99)(1-1)(1+0) \cdots(1+11)-1=-1 \text {. }

Solve:
i=12013mi=(1+1)(1+99)(11)(1+0)(1+11)1=1 \sum_{i=1}^{2013} m_{i}=(1+1)(1+99)(1-1)(1+0) \cdots(1+11)-1=-1 \text {. }

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