They are SQUARE NUMBERS.
For English speaking people, the numbers are in alphabetical order.
The numbers are in alphabetical order of their names in the English language.
499 + 49
Two numbers with a sum of 4 and a difference of 9 are -6.5 and 2.5.
They are SQUARE NUMBERS.
They are all perfect square numbers.
They are 'square' numbers. 6x6=36, 9x9=81 and 5x5=25. Some other square numbers are 64, 4, 9, 100 & 121
For English speaking people, the numbers are in alphabetical order.
The numbers are 4 and 5: 4 + 5 = 9
The numbers are in alphabetical order of their names in the English language.
Sure. But since negative numbers have positive factors and positive numbers are greater than negative numbers, the answer will be the same regardless of the sign. The GCF of 4 and 9, -4 and 9, 4 and -9 and -4 and -9 is 1.
13
It is any sequence of numbers. For example: 1 3 5 7 9 11 .... - this is the sequence of odd numbers. 1 4 65 4556 4 3 76 ... - this is probably not a special sequence at all.
499 + 49
8 5 4 9 1 7 6 10 3 2 0 This sequence is special because the numbers are in alphabetical order. The Fibonacci sequence is very special and the triangular sequence.
Two numbers with a sum of 4 and a difference of 9 are -6.5 and 2.5.