A few years ago it was a big thing where high school basic math definition stumped a lot of pro mathematicians. The prob from memory involved order of operations. Could be wrong but I think it was getting the correct answer to; a(b+c) for specific values of a,b,c. All integers and no tricks. Some maths profs argued for their answer some changed but the only answer was it was not a well defined question. Few conceded the other guy was right, or how they were wrong. Sorry I can't define the actual problem but it started a math educator war. Hope my vague definition triggers someone's memory.