I am a four-digit number. If you multiply me by 4, my digits completely reverse their original order. What number am I?
2178
2178 multiplied by 4 equals 8712, which is the exact digit reversal of 2178.
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.
More math riddles
Stand me up and I am a digit of great power, but lay me down on my side and I become endless. Take away my top half and I become a zero. What number am I?
If 5 machines take 5 minutes to produce 5 items, how long would it take 100 machines to produce 100 items?
Omar counts rabbits in a pattern: 4, 7, 10, 13. How many rabbits come next?
Three friends share a pizza cut into 12 slices. Alice eats twice as many slices as Bob, and Charlie eats three times as many slices as Bob. How many slices does Alice eat?
I am a fraction. My numerator is the only even prime number, and my denominator is the smallest odd composite number. What fraction am I?
One firework costs 3 dollars. How many dollars do 3 fireworks cost?