self Maths Puzzle

There is a number that is 3 times the sum of its digits. What is this number?

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self Other Question

"Dad, where had you been?" asked Graham.

"I had been to the attic, my son," replied Dad. "And do you know what I saw there? There was a big web with 15 spiders and flies on it."

"How many spiders were there?" asked the little boy with curiosity.

"Well, there were a total of 100 legs on the web," answered Dad with a smile. "Now you can find out how many spiders were there by yourself. Can't you?"

Can you help the little boy find out how many spiders were on the web in the attic?
Consider 10 lines drawn at a tangent to an ellipse. The lines break up the plane into several regions, some bounded (i.e., enclosed) and others unbounded. How many unbounded regions are there?