Did you know you can make a minus account by adding numbers?

As much as we all now have easy access to our cell phone calculators, there are certain times in our lives when we are forced to test the basic math skills we have learned in school. Whether during a test, a time when our smartphone is out of battery or in another restrictive situation, sooner or later we will face dull tasks like subtracting 245871 from 785412.

When trying to make a minus account with large numbers, we are forced to use those old rules that dictate gradual house-to-house “loans, ” which is not only rather boring but also takes considerable time. With that in mind, the MinutePhysics YouTube channel decided to teach a simple method for subtracting large numbers - and, most strikingly, this system involves performing a sum.

The idea is to make small subtractions of 9 with each digit from the smallest number of your account except the last one, which will be subtracted from 10. Following the example we gave in the first paragraph, we would have the following accounts based on the original number 245871:

  • 9 - 2 = 7
  • 9 - 4 = 5
  • 9 - 5 = 4
  • 9 - 8 = 1
  • 9 - 7 = 2
  • 10 - 1 = 9

Then the resulting number - 754129, in this case - is added to the largest value of the original account - which for us is 785412. After doing this operation, just ignore the first digit of the result of this addition to reach the final value of the subtraction that we wanted to solve. Continuing our example, we would have the following:

  • 785412 + 754129 = 1539541

Cutting off the first 1, the result of the account is 539541.

If you don't understand the sum subtraction method or are still finding the idea too complicated, it's worth checking out the video above for a demo. Although we are used to doing less accounts more traditionally, this system turns out to be faster for large number operations. Although it also works for smaller values, in these cases the method is longer.

According to MinutePhysics, the idea is also similar to the method used by computers to do these accounts, except that PCs use binary numbers to perform these operations. So what did you think of this math witchcraft? Do you think you will apply the concept in your daily life? Leave your opinion in the comments.