Answer: A. 0.874387438743.. is  a rational number.
Step-by-step explanation:
Since Any number that can be written in fraction form is a rational number if it can be in the form of p/q where p and q are integers and q≠0
Since we can write 0.874387438743... = 
Where, 8743 and 9999 are integers and 9999≠0
Thus, 0.874387438743... is a rational number.
But, 0.0000100020003... ,  5.891420975..... and 10.07401259... can not be written in the form of p/q therefore they are not the rational number.
Therefore, Only Option A is correct.
 
        
             
        
        
        
Answer:
507.60
Step-by-step explanation:
42.30 X 12 = 507.60
 
        
             
        
        
        
<h2>
Answer:</h2>
4.82 × 10⁻⁴
<h3>
Explanation:</h3>
Move the decimal so there is one non-zero digit to the left of the decimal point. The number of decimal places you move will be the exponent on the  10
. If the decimal is being moved to the right, the exponent will be negative. If the decimal is being moved to the left, the exponent will be positive.
 
        
        
        
Answer:
6*5 = 30
Step-by-step explanation: