Open Middle®
Directions: Using the digits 1-9, subtract two numbers to get a difference closest to 0.
Hint
What is your plan for the digits? Where should you place them? What does it mean for a decimal to be close to 0?
Answer
There could be multiple answers, but we have only found one so far. It is 21 – 19.8 = 1.2
Source: Owen Kaplinsky
Why is the difference (answer) shifted to the right so that the decimal points are misaligned? Are the instructions to use digits more than once? Or can you use the digits only one time? The answer shows multiple up to 3 digits being used, yet the example leads people to use only two digit numbers at each level. Finally, the answer shows 21 as the minuend, yet the example falsely makes me think that I should be using a decimal, like 2.1. Thank you.
Sorry, we’ve fixed this image.
The boxes above are misleading. Your answer: 21 – 19.8 = 1.2 uses 5 digits in your problem, however you only used a model with 4 boxes. Confusing for students. Please add the extra boxes in your problem.
Sorry, we’ve fixed this image.
Sorry…. I don’t see how this image was corrected. It looks like the same problem.
4. 12 – 3.98 is what I found.
Nice! That’s what I got too!
Nice! That’s what I got too!
I think the image is not showing on the page. Like the problem though!
I don’t understand. Why not 2-1.987654321?
Or, 2-1.98765431 I guess.