School-Safe Puzzle Games

## Quick arithmetic puzzle

What digit, used 4 times, can be arranged so as to ad up to 100?

### 17 Comments to “Quick arithmetic puzzle”

1. Daniel | Guest

Five. (5 + 5) x (5 + 5) = 10 x 10 = 100

2. Sal | Guest

99 + 9/9 =100

3. Jonathan Pantiesbrough | Guest

The number 5. 55+55-5-5=100.

4. John Lewis Highsmith | Guest

The digit is 9. Do you digit?

5. Slavco | Guest

I think it is number 4:

0 = 4+4-4-4
1 = (4+4)/(4+4)
2 = (4*4)/(4+4)
3 = (4+4+4)/4
4 = 4+[(4-4)/4]
5 = [(4*4)+4]/4
6 = 4+[(4+4)/4]
7 = (4+4)-(4/4)
8 = [(4+4)*4]/4
9 = (4+4)+(4/4)

….

6. Slavco | Guest

To get other numbers you need to combine 2 number 4, to make a “44”…

10 = (44 – 4)/4

Im guessing that you will also use a square root funcion, which to my opnion shouldn’t be right, because if you are using a square root you would need a number 2 indicating that it is square……..

The really challenging part would be doing it without a square root….(i’m not even sure if it could be done)

7. Mark W | Guest

well… it’s not adding, but 99/.99=100

as does 88/.88=77/.77=…..=22/.22=11/.11=100

8. James D. Turner | Guest

Ques. do powers count! If not then:

5^4/5 -5*5 = 100

9. Dan Harris | Guest

[(5×5)-5] x 5

or

P + P + P + P in base 25 or higher, if you absolutely need it to be “addition.”

10. Scott K | Guest

9: 99 and 9/9ths

11. J Tanedo | Guest

do they have to be whole numbers? (55 – 5) / .5 , i know its probably not it, but meh

12. J Tanedo | Guest

oh, nvm, [(5 * 5) – 5] * 5

13. Ian | Guest

4
4!x4+square route of 4+ square route of 4
\
(4x3x2x1)

14. deejam | Guest

15. RK | Profile

16. suineg | Guest

i think 9 is one answer: 99+(9/9)=100, but another a little bit more complicated is this one (7+7)*(7+7^-1), that became (14)*(7+ 1/7)–>98+2—->100, i used 7 because nobody else used that number, but i think there are plenty of possible answers

17. Sanjay | Guest

I’m guessing the question has a play on words, so the answer is 5:

5 is a digit, arranged like this: 5+5+5+5+5 (or 5×5).

And if used 4 times: (5 x 5) x 4

adds up to 100 (25 + 25 + 25 + 25)

Just my thoughts