Math Riddles for High School Students Ready to Strategize

I am a three-digit number. My tens digit is twice my ones digit. My hundreds digit is the tens digit minus three. What number am I?

Add me to myself and multiply by four. Divide by eight and you have me again. What number am I?

The sum of two numbers is 26 and their difference is 6. What are the numbers?

If five cats can catch five mice in five minutes, how many cats are needed to catch 50 mice in 50 minutes?

I am a number that becomes 20 when tripled and then decreased by 4. What number am I?

A digital clock shows the same hour and minute digits (like 11:11). How many times does this happen in 24 hours?

What integer satisfies: three times it plus five equals twice it plus 17?

I am a palindrome number divisible by 3 and 11, between 400 and 500. What am I?

A train leaves at 3:15 p.m. traveling 45 mph. Another leaves the same station at 3:45 p.m. at 60 mph on the same track. When will the faster train catch the slower one?

How many diagonals does a regular 12-sided polygon have?

A triangle has angles in the ratio 2:3:4. What are the measures?

If the average of four numbers is 18 and three of them are 12, 20, and 26, what is the fourth?

I am a two-digit prime number that becomes composite if you reverse my digits. What number am I?

The product of two consecutive integers is 132. What are the integers?

A sequence starts 2, 6, 12, 20. What is the next term?