The puzzle looks simple: start with 1000, then add 40, 1000, 30, 1000, 20, 1000, and finally 10. There is no calculator or paper allowed, only mental math. That small challenge encourages people to answer quickly, and many confidently say 5000. But that answer is incorrect.

The correct way is to follow the numbers exactly as they appear. Start with 1000 and add 40 to get 1040. Add another 1000 for 2040, then 30 for 2070. Add 1000 to reach 3070, then 20 to reach 3090. Another 1000 makes 4090, and adding the final 10 gives **4100**. As the original explanation says, **“Four groups of 1000 make 4000. The smaller amounts—40, 30, 20, and 10—make 100.”** Together, they equal 4100.

The reason so many people choose 5000 is that the brain naturally looks for patterns and round numbers. After seeing several 1000s, people may expect another 1000 at the end instead of paying attention to the actual number 10. The instruction to do it “just your mind” can make this mistake even easier because people rush instead of checking each step.

The puzzle is not really about difficult mathematics. It tests whether you can slow down and follow the information exactly as presented. The original article puts it clearly: **“The phrase ‘just your mind’ makes people skip the only method that works: one step at a time.”**

So, if you see this puzzle online, do not let the pattern fool you. Add every number in order, and the answer is **4100—not 5000**.