Riddle: One is to three as three is to five and five is to four and four is the magic number.  What is the pattern?
Answer: One has three letters in the word three has five letters in it five has four letters and four has four letters in it (if you try more numbers they will always come back to the number four: so four is the magic number)
Math Riddles: One is to three as three is to five and five is to four and four is the magic number.  
What is the pattern? Riddle Meme.
Riddle: What did the triangle say to the circle?
Answer: You’re pointless.
Riddle: If a boy blows 18 bubbles, Then pops 6 eats 7 and then He pops 5 and blows 1. How many are left?
Answer: 1.
If a boy blows 18 bubbles,  Then pops 6 eats 7 and then  He pops 5 and blows 1.  How many are left? Riddle Meme.
Riddle: The ages of a father and son add up to 66. The father's age is the son's age reversed. How old could they be? (3 possible solutions).
Answer: 51 and 15. 42 and 24. 60 and 06.
Riddle: What two whole, positive numbers that have a one-digit answer when multiplied and a two-digit answer when added?
Answer: 1 and 9.
What two whole, positive numbers that have a one-digit answer when multiplied and a two-digit answer when added? Riddle Meme.
Riddle: Pick a number from 1-10, multiply it by 2, add ten, divide it by 2, now subtract the number that you have from the number you picked. What is it?
Answer: Do you have 5?
Riddle: You want to boil a two-minute egg. If you only have a three-minute timer (hourglass), a four-minute timer, and a five-minute timer, how can you boil the egg for only two minutes?
Answer: Once the water is boiling, turn the three-minute timer and five-minute timer over. When the three-minute timer runs out, put the egg in the boiling water. When the five-minute timer runs out, two minutes have elapsed and it is time to take the egg out of the water. You don't need the four-minute timer for this riddle.
You want to boil a two-minute egg. If you only have a three-minute timer (hourglass), a four-minute timer, and a five-minute timer, how can you boil the egg for only two minutes? Riddle Meme.
Riddle: 81 x 9 = 801. What must you do to make the this equation true?
Answer: Turn it upside down.  108 = 6 x 18.
Riddle: How much will a 38° angle measure when looked at under a microscope that magnifies ten times?
Answer: It will still be 38°.
Riddle: 1=5, 2=15, 3=215, 4=3215, 5=?
Answer: 5=1, because 1=5.