The Newest Prime Number
An Investigation
The Newest Prime Number
The newest prime number is
21257787 - 1
If this number was to be
written out in full what would
the last two digits be?
Solution
The table on the next slide shows how
the solution is worked out.
n
Last two digits of 2n -1
n
Last two digits of 2n -1
1
1
2
3
3
7
4
15
24
15
5
31
25
31
6
63
26
63
7
27
27
27
8
55
28
55
9
11
29
11
10
23
30
23
11
47
31
47
12
95
32
13
91
33
14
83
34
15
67
35
16
35
36
17
71
37
18
43
38
19
87
20
75
21
51
22
03
23
07
etc
Solution
Using the above table we see that the
last two digits of 21257787 – 1 are 27