Correct option is A)
Clearly, the required number is the HC.F of the numbers
626−1=625,3127−2=3125 and 15628−3=15625.
Using Euclid's division lemma to find the H.C.F. of 625 and 3125.
3125=625 × 5+0
Clearly, H.C.F. of 625 and 3125 is 625.
Now, H.C.F. of 625 and 15625
15625=625 × 25+0
So, the H.C.F of 625 and 15625 is 625
Hence, H.C.F of 625,3125 and 15625 is 625.
Hence, the required number is 625.