Without specifying any limits on the number of uses of each digit and how many digits can be in the answer there are an infinite number of number that can be made using the digits {3, 5, 6, 1}.
If the number has to be 4 digits long and each digit can only be used once, there are 24 numbers:
1356, 1365, 1536, 1563, 1635, 1653,
3156, 3165, 3516, 3561, 3615, 3651,
5136, 5163, 5316, 5361, 5613, 5631,
6135, 6153, 6315, 6351, 6513, 6531.
If the number is 4 digits long and a digit can be repeated, then there are 256 numbers:
1111, 1113, 1115, 1116, 1131, 1133, 1135, 1136, 1151, 1153, 1155, 1156, 1161, 1163, 1165, 1166,
1311, 1313, 1315, 1316, 1331, 1333, 1335, 1336, 1351, 1353, 1355, 1356, 1361, 1363, 1365, 1366,
1511, 1513, 1515, 1516, 1531, 1533, 1535, 1536, 1551, 1553, 1555, 1556, 1561, 1563, 1565, 1566,
1611, 1613, 1615, 1616, 1631, 1633, 1635, 1636, 1651, 1653, 1655, 1656, 1661, 1663, 1665, 1666,
3111, 3113, 3115, 3116, 3131, 3133, 3135, 3136, 3151, 3153, 3155, 3156, 3161, 3163, 3165, 3166,
3311, 3313, 3315, 3316, 3331, 3333, 3335, 3336, 3351, 3353, 3355, 3356, 3361, 3363, 3365, 3366,
3511, 3513, 3515, 3516, 3531, 3533, 3535, 3536, 3551, 3553, 3555, 3556, 3561, 3563, 3565, 3566,
3611, 3613, 3615, 3616, 3631, 3633, 3635, 3636, 3651, 3653, 3655, 3656, 3661, 3663, 3665, 3666,
5111, 5113, 5115, 5116, 5131, 5133, 5135, 5136, 5151, 5153, 5155, 5156, 5161, 5163, 5165, 5166,
5311, 5313, 5315, 5316, 5331, 5333, 5335, 5336, 5351, 5353, 5355, 5356, 5361, 5363, 5365, 5366,
5511, 5513, 5515, 5516, 5531, 5533, 5535, 5536, 5551, 5553, 5555, 5556, 5561, 5563, 5565, 5566,
5611, 5613, 5615, 5616, 5631, 5633, 5635, 5636, 5651, 5653, 5655, 5656, 5661, 5663, 5665, 5666,
6111, 6113, 6115, 6116, 6131, 6133, 6135, 6136, 6151, 6153, 6155, 6156, 6161, 6163, 6165, 6166,
6311, 6313, 6315, 6316, 6331, 6333, 6335, 6336, 6351, 6353, 6355, 6356, 6361, 6363, 6365, 6366,
6511, 6513, 6515, 6516, 6531, 6533, 6535, 6536, 6551, 6553, 6555, 6556, 6561, 6563, 6565, 6566,
6611, 6613, 6615, 6616, 6631, 6633, 6635, 6636, 6651, 6653, 6655, 6656, 6661, 6663, 6665, 6666
There are 24:1356 1365 1536 1563 1635 1653
3156 3165 3516 3561 3615 3651
5136 5163 5316 5361 5613 5631
6135 6153 6315 6351 6513 6531.
Total number of possible 3-digit numbers = 9!x10!10!
7
Yes, it is. 5/1 equals 5.
Using the formula n!/r!(n-r)! where n is the number of possible numbers and r is the number of numbers chosen, there are 13983816 combinations of six numbers between 1 and 49 inclusive.
The four digits can be used to produce infinitely many different numbers if repetition is permitted. Without repetition, there are 24 possible numbers. A lot more can be produced if the numbers are combined using binary oprations, fore example, 19 * 8/4 = 19*2 = 38.
Total number of possible 3-digit numbers = 9!x10!10!
7
One possible pair of numbers is 1 and 60.
One possible answer is 194 + 6
Yes, it is. 5/1 equals 5.
Using the formula n!/r!(n-r)! where n is the number of possible numbers and r is the number of numbers chosen, there are 13983816 combinations of six numbers between 1 and 49 inclusive.
Using various mathematical techniques, this is possible.
Using only sums and differences, and not necessarily all four numbers, 1, 3, 9 and 27 will make all numbers from 0 to 40.
The four digits can be used to produce infinitely many different numbers if repetition is permitted. Without repetition, there are 24 possible numbers. A lot more can be produced if the numbers are combined using binary oprations, fore example, 19 * 8/4 = 19*2 = 38.
Impossible, as there are not enough numbers to cover all squares.
Just 1.
46