2 groups
You can lay the blocks out of decimal numbers by putting the numbers in groups.
NOTHING!
by rounding off the numbers
No.
3112331 and 251519 are prime.
C (251519) and B (3112331) are both prime. A (2359) is a multiple of 7 and D (7172949) is a multiple of 3. But, without the number for which they could be a factor, it is only possible to identify the prime numbers, not the one that is a prime factor.
odd numbers
the dimensionless numbers have the definition as that of dimensionless groups, and have all the properties which dimensionless groups have.
There are 6 groups.
2 groups
You can lay the blocks out of decimal numbers by putting the numbers in groups.
NOTHING!
Both are part of the real numbers.
by rounding off the numbers
Factors.
No.