Make the Number 100 - Solution

Make the Number 100 - Solution

The Puzzle: Using the numerals 1,7,7,7 and 7 (a "1" and four "7"s) create the number 100.

As well as the five numerals you can use the usual mathematical operations (+, -, x, and brackets ().

For example: (7+1) (7+7) = 112 would be a good attempt, but not right, because it is not 100.

The Solution . . .

We know of two solutions:

a) 177-77 = 100b) (7+7) (7+(1 7)) = 100

Birthday - Solution

The Puzzle: When asked about his birthday, a man said:

"The day before yesterday I was only 25 and next year I will turn 28."

This is true only one day in a year - when was he born?

The Solution . . .

He was born on December 31st and spoke about it on January 1st.

5-digit Number - Solution

The Puzzle: What 5-digit number has the following features:

If we put the numeral 1 at the beginning, we get a number three times smaller than if we put the numeral 1 at the end of the number.

The Solution . . .

Using an easy equation:

3(100000 + x) = 10x+1

(Why? Well, adding 100000 puts a 1 at the front of a five-digit number, and multiplying by 10 and adding 1 puts a 1 at the end of a number)

Solving this gives:

10x+1 = 3(100000 + x) 10x+1 = 300000 + 3x 10x = 299999 + 3x7x = 299999x= 299999/7 = 42857

The answer is 42857.

Tricky Equation - Solution

The Puzzle: The following equation is wrong: 101 - 102 = 1

Move one numeral to make it correct.

(Caution: Trick)

The Solution . . .

Move the numeral 2 half a line up to achieve 101-102 = 1

Fraction - Solution

The Puzzle: Can you arrange the numerals 1 to 9 (1, 2, 3, 4, 5, 6, 7, 8 and 9) in a single fraction that equals exactly 1/3 (one third)?

Example that doesn't work: 7192/38456 = 0.187

The Solution . . .

5832/17496 = 1/3

Choose the Right Symbol - Solution

The Puzzle: What mathematical symbol can be put between 5 and 9, to get a number bigger than 5 and smaller than 9?

(Caution: Trick)

The Solution . . .

A Decimal Point

5.9 works nicely

24 from 8,8,3,3 - Solution

The Puzzle: How can I get the answer 24 by only using the numbers 8,8,3,3.

You can use the main signs add, subtract multiply and divide.

(Puzzle supplied by "Steve123")

The Solution . . .

We know of two solutions.

1) Supplied by "mathsyperson":

8/(3-(8/3))=8/(1/3)=24

2) Supplied by "puzzler09", using factorials:

((8 x 3!)/3)+8

= ((8 x 3 x 2 x 1)/3)+8= (48/3)+8= (16)+8= 24

Sum Of Digits is 43 - Solution

The Puzzle: I am thinking of a 6-digit number. The sum of the digits is 43.

And only two of the following three statements about the number are true:

(1) it's a square number,(2) it's a cube number, and(3) the number is under 500000.

.

The Solution . . .

Only Statements 1 and 3 are true. the number is 499849.

7072 = 499849 499849