If a is a positive integer, and if the units' digit of a^2 is 4 and the units' digit of (a + 1)^2 is 1, what is the units' digit of (a + 2)^2 ?
Select.
A) 0  B) 2  C) 4  D) 6  E) 8
A for me.   _1² = _1   _2² = _4   _3² = _9   _4² = _6   _5² = _5   _6² = _6   _7² = _9   _8² = _4   _9² = _1   _0² = _0   On the list, the only number that squared has the units digit = 4 preceding a number that squared has the units digit = 1 is the _8.   So, a = _8, that has square 4. The next square is 1 andnext nextsquare is 0.
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If a is a positive integer, and if the units' digit of a^2 is 4 and the units' digit of (a + 1)^2 is 1, what is the units' digit of (a + 2)^2 ?