Here are some problems you can try to solve. I think it doesn't require much knowledge, but mostly tricks.
#1 : simple algebra
Less than 12 years ago, a mathematician, Vincent Urri, told his niece :
- It's curious ! I have in front of me 3 positive integers. Their product is equal to my age and their sum gives your age !
The niece, though she's good at calculations, wasn't able to guess what the 3 numbers were.
This year, Vincent Urri has just turned 100 years old. How old is his niece today ?
#2 : a little of number theory
1. What is the remainder in the division of by 7 ?
2. What is the remainder in the division of by 11 ?
3. What is the remainder in the division of (where there are 502 times the pattern 2008) by 37 ?
#3 : simple geometry
The Swedish flag has a yellow cross of constant width in a blue background. The yellow area represents one third of the flag's area.
If the flag is 1m long and 66cm wide, what is the width of the yellow stripes ?
#4 : aŁg€bra
Teddy left his 9-digit code of his safe box in his safe box !
Luckily, he recalls that the code doesn't have any 0, that the numbers are all different and that :
- the number formed by the first 2 digits is a multiple of 2
- the number formed by the 2nd and the 3rd digits is a multiple of 3
- the number formed by the 3rd and the 4th digits is a multiple of 4
- and so on... until the number formed by the 8th and the 9th digits, multiple of 9.
With this information, he finds out 2 possibilities. What are they ?