Answer:
Following entries can be regarded as numbers:
1.56e-9
1.9435
-4.99
Explanation:
According to the given rules, only "e" can be used for show power of 10. Furthermore, using space between numbers and including units (without justification) are not allowed. Under these rules let us consider each number given.
1) 1.56e-9
This satisfies all three conditions given above and hence, is a number. Simplified value is
2) 3.25E4
As we can only use "e" for exponents, use of "E" is wrong, therefore this entry cannot be considered as a number.
3) 2.54 m
Here a space and a unit "m" (meter - unit of length) is used and therefore this entry cannot be considered as a number.
4) 1.56 e-9
Here a space is used due to which this value is not declared a number.
5) 1.9435
This again satisfies all conditions and therefore is a number.
6) -4.99
This is also a number as the use of + or - sign is allowed.
7) 1.23 inches
Here a space and a unit "inches" (unit of length) is used again and therefore this entry is also not a number.