Interesting property with 9

I want to get clarified with numbers ending with 9. I have considered 2 digit numbers and not extending it further as of now.

If we have 2 digit numbers of the form 10a + b and ending with 9,

Then, $ab + a+b= 10a+b$ .

#NumberTheory

Easy Math Editor

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Comments

I assume that $a$ is a single digit positive integer and $b$ is a non-negative single digit integer, then obviously $b=9$ and so your equation holds true.