Question

Find the squares for each of the following using the method of squaring a 2-digit number having units
digit as 5.
b 75
d 25
e 65
a 45
c 95​

Answer 1

75 squared

As it ends in _5 we know the answer ends in _25 so we just need to calculate the leading digits.

The tens digit is 7, so we multiply it by the next larger digit, which is 8.

\begin{equation*} \begin{split} 7 + 1 &= 8\\ 7\times 8 &= 56 \end{split} \end{equation*}

And there we have our leading digits, so the answer to our problem is:

\[ 75^2 = \textcolor{Red}{56}25 \]