Happy New Prime Year

2011!Pilar Oliva

About prime numbers 11 is a prime number 2011 is a prime number too; it has no divi-sors,but... 2, 3 , 5, 7, 11, 13 are the first six prime numbers Try to calculate them, by using each digit of 2011 and the signs +, -, x and / once .

For instance, 2 = 2 + 0x1x1

Now, think about counting two by two instead of ten by ten; this is the numeration system called base two.1 is 12 is 103 is 11

What would 4 be ? 4 is 100Because 4 = 1x22 + 0x21 + 0x1Then think about the first day of the year.01/01/11It is 010111 in base 2;what is its value in the

decimal numeration system ? 0x25+1x24+0x23+1x22+1x21+1x1=2323 is also a prime number!

Think about another day of January that could be a number in base two and try to write it as a decimal number.

Hint

Answer

Think about the first two days at school af-ter Christmas Holiday .

Go to the previous page

37 is another prime number!

55 is not a prime number, because it is a multiple of 5 and 11.