# What number should replace the question mark? 10 Math Riddle, Math Puzzles With Answer 10 Math Riddle

# 10 Math Riddle

**10 Math Riddle**** If a hen and a half lay an egg and a half in a day and a half, how many eggs will half a dozen hens lay in half a dozen days? **

**Math Riddle: 1 Which number is the odd one out?**

**9678 4572 5261 5133 3527 6895 7768**

**Answer: 3527.**

**Solve: In the others, the sum of the first two numbers is equal to the sum of the second two numbers for example 5 + 2 = 6 + 1**

**Math Riddle:2 If a hen and a half lay an egg and a half in a day and a half, how many eggs will half a dozen hens lay in half a dozen days?**

**Answer: Two dozen. If you increase both the number of hens and the amount of time available four-fold, the number of eggs increases 16 times. 16 x 1.5 = 24.**

**Math Riddle:3 A small number of cards has been lost from a complete pack. If I deal with four people, three cards remain. If I deal with three people, two remain and if I deal with five people, two cards remain. How many cards are there?**

**Answer: There are 47 cards.**

**Math Riddle: 4 You know 2 + 2 comes to the same as 2 x 2. Now find a set of three different whole numbers whose sum is equal to their total when multiplied.**

**Answer: The three different whole numbers whose sum is equal to their total when multiplied are 1, 2, and 3.**

**Math Riddle: 5 What number should replace the question mark?**

**0, 4, 2, 6, 3, 7, 3, 5, ?**

**Answer: 7.5.**

**Solve: The sequence proceeds + 4, ÷2, + 4, etc.**

**Math Riddle: 6 John noticed that the amount he was paying for his lunch was a rearrangement of the digits of the amount of money he had in his pocket and that the money he had leftover was yet another rearrangement of the same three digits! How much money did John start with?**

**Answer: John started at $9.54. The money can be written with just three digits—so it must be between $1.01 and $9.99. Trial and error show that there is only one set of numbers that fit this question: $9.54 = $4.59 + $4.95. If you can solve these math riddles easily.**

**Math Riddle:7 What number should replace the question mark?**

**24, 30, ?, 60, 84, 114**

**Answer: 42**

**Solve: The sequence progresses +6, +12, +18, +24, +30**

### Try To Solve: 25 Brain teasers for adults

**Math Riddle: 8 One brother says of his younger brother: “Two years ago, I was three times as old as my brother was. In three years’ time, I will be twice as old as my brother.” How old are they each now?**

**Answer: The elder is 17, the younger 7. Two years ago, they were 15 and 5 respectively, and in three years’ time, they will be 20 and 10.**

**Math Riddle: 9 Complete this sequence?**

**2 3 4 9 16 81 256**

**Answer: 6561.**

**Solve: There are two sequences arranged alternately. In each sequence, the number is the square of the previous number in that sequence. 6,561 is the square of 81.**

**Math Riddle: 10 What is X? (****X 11 1098 76 5 43 21)**

**Answer: 12**

**Solve: The series must be read backward and spaced correctly :**

**1 2 3 4 5 6 7 8 9 10 11 12 (X)**