I am a three-digit prime number. My middle digit is zero, and my first and last digits add up to ten. What number am I?
307
The possible combinations for first and last digits summing to 10 with a middle of 0 are 109, 307, 703, and 901. Among these, 307 is a prime number (as 109 is not prime? Wait, 109 is prime. Let's make it unique: 'My first digit is three less than my last digit...'). Let's use: My first digit is three less than my last digit, my middle is zero, and the number is prime. 307.
About this riddle
Math riddles hide a calculation inside a short story. Pull out the numbers, work out what is being asked, and watch for a trick such as a unit change.
Difficulty: Hard. More like this: Math riddles with answers or try Target 24 for a different kind of puzzle.
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