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    Sum Of Two Digit Number Is 9 When We Interchange

    We’ve all heard the old adage that “the sum of two digit number is 9 when we interchange them”. But what exactly does this mean? While it may sound like a simple trick, there is an underlying logic to it. In this blog post, we’ll explore the mathematics behind this statement and look at some examples of how it works in practice. We’ll also discuss why this rule holds true in certain cases and not others. So read on to learn more about the mysterious “sum of two digit number is 9 when we interchange them”!

    Digit numbers whose sum is 9

    There are many digit numbers whose sum is 9. For example, 18 and 27 are two such numbers. When we interchange the digits of these numbers, we get 81 and 72 respectively. The sum of these two numbers is 9.

    Similarly, there are many other digit numbers whose sum is 9. Some of them are: 36 and 45, 54 and 63, 72 and 81, 99 and 90 etc. We can see that in all these cases, the sum of the digits remains 9 even after interchanging them.

    Interchanging the digits

    When we interchange the digits of a two-digit number, the resulting number is called an exchange number. The sum of a two-digit number and its exchange number is always equal to 99. For example, consider the number 42. When we interchange its digits, we get 24. The sum of 42 and 24 is 66.

    We can use this property to find the sum of any two-digit number without actually having to add the numbers together. For example, to find the sum of 35 and 47, we first interchange the digits of 35 to get 53. Then, we add 53 and 47 to get 100. Finally, we subtract 1 from 100 to get 99, which is the sum of 35 and 47.

    The resulting number

    The resulting number is the number that we get when we add two numbers together. In this case, we are summing the digits of a two-digit number. The resulting number will be the same regardless of whether or not we interchange the digits.

    Why this happens

    This happens because when we add two digits together, we are really just adding two single-digit numbers. However, when we interchange the digits, we are effectively changing the order in which they are added. This can cause a different result.


    We have seen how to find the two numbers when we know that their sum is 9 and that they need to be interchanged. We discussed the strategies for solving this problem, as well as some of its applications in real-life scenarios. Understanding the concept behind this math problem is an important skill to have, especially if you are a student or teacher. Knowing how to solve these types of problems will come in handy in everyday life, so it’s definitely worth learning!


    When it comes to math, two digit numbers can be quite tricky! Luckily, there are a few tricks that can help us out. One of these tricks is when the sum of two digits is 9, we can interchange them to arrive at the same result.

    Let’s see how this works with an example. Let’s say we have the number 36. The sum of the two digits is 3 + 6 = 9. So, if we interchange the numbers, we will get the same result – 63. In other words, both 36 and 63 have the same sum of 9.

    This is a great trick to remember when it comes to two digit numbers. It can be especially helpful when solving problems such as addition, subtraction, and multiplication. By interchanging the digits, we can arrive at the same result as before!

    So next time you come across two digit numbers, remember this trick and it’ll help you solve the problem quickly and easily. And don’t forget to have fun with math!

    Happy math-ing!

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