if a is a positive integer, and if the unit's digit of a^2 is 9 and the unit's digit of (a+1)^2 is 4, what is the unit's digit of (a+2)^2 ?
a. 1
b. 3
c. 5
d. 7
e. 9
answer is A
a. 1
b. 3
c. 5
d. 7
e. 9
answer is A
