Number Sequences

Number Sequences

There are infinite formulas that will fit any finite series. Try to guess the following number in each sequence (using the most simple mathematical operations there is more than one solution for each number sequence). Solutions are at the bottom of the page.




8723, 3872, 2387, ?
1, 4, 9, 18, 35, ?
23, 45, 89, 177, ?

7, 5, 8, 4, 9, 3, ?
11, 19, 14, 22, 17, 25, ?
3, 8, 15, 24, 35, ?
2, 4, 5, 10, 12, 24, 27, ?
1, 3, 4, 7, 11, 18, ?
99, 92, 86, 81, 77, ?
0, 4, 2, 6, 4, 8, ?
1, 2, 2, 4, 8, 11, 33, ?
1, 2, 6, 24, 120, ?
1, 2, 3, 6, 11, 20, 37, ?
5, 7, 12, 19, 31, 50, ?
27, 82, 41, 124, 62, 31, 94, 47, 142, 71, 214, 107, ?
126, 63, 190, 95, 286, 143, 430, 215, 646, 323, 970, ?
4, 7, 15, 29, 59, 117, ?
2, 3, 2, 3, 2, 4, 2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 4, 2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 4, 2, 3, 2, 3, 2, 5, ?
4, 4, 341, 6, 4, 4, 6, 6, 4, 4, 6, 10, 4, 4, 14, 6, 4, 4, 6, 6, 4, 4, 6, 22, 4, 4, 9, 6, ?

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Solutions
8723, 3872, 2387, ? 7238 (moving of numerals)

1, 4, 9, 18, 35, ? 68 (x*2+2, +1, +0, -1, -2)
23, 45, 89, 177, ? 353 (x*2-1)
7, 5, 8, 4, 9, 3, ? 10, 2 (two series – every second number: 7, 8, 9, 10 and 5, 4, 3, 2)
11, 19, 14, 22, 17, 25, ? 20, 28 (two series – every second number: 11, 14, 17, 20 and 19, 22, 25, 28)
3, 8, 15, 24, 35, ? 48 (x+5, +7, +9, +11, +13)
2, 4, 5, 10, 12, 24, 27, ? 54, 58 (x*2, +1, *2, +2, *2, +3, *2, +4)
1, 3, 4, 7, 11, 18, ? 29 (a+b=c, b+c=d, c+d=e …)
99, 92, 86, 81, 77, ? 74 (x-7, -6, -5, -4, -3)
0, 4, 2, 6, 4, 8, ? 6 (x+4, -2, +4, -2, +4, -2)
1, 2, 2, 4, 8, 11, 33, ?
1, 2, 6, 24, 120, ? 720 (x*2, *3, *4, *5, *6)
1, 2, 3, 6, 11, 20, 37, ?
5, 7, 12, 19, 31, 50, ? 81 (a+b=c, b+c=d, c+d=e …)
27, 82, 41, 124, 62, 31, 94, 47, 142, 71, 214, 107, ? 322, 161 (x*3+1, /2, *3+1, /2 …)
126, 63, 190, 95, 286, 143, 430, 215, 646, 323, 970, ? 485, 1456 (x/2, *3+1, /2, *3+1 …)
4, 7, 15, 29, 59, 117, ? 235 (x*2-1, *2+1, *2-1 …)
2, 3, 2, 3, 2, 4, 2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 4, 2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 2, 4, 2, 3, 2, 3, 2, 5, ? 2, 3, 2, 3, 2, 4, 2, 3, 2, 3, 2, 5
4, 4, 341, 6, 4, 4, 6, 6, 4, 4, 6, 10, 4, 4, 14, 6, 4, 4, 6, 6, 4, 4, 6, 22, 4, 4, 9, 6, ? 4, 4