To compute \( 987654321 \) squared exactly, simply multiply \( 987654321 \) by itself:

\[ 987654321 \times 987654321 \]

Use the basic multiplication formula:
\[ (a \times a) = a^2 \]

Plugging in the numbers:
\[ (987654321)^2 = 975461057789971041 \]

So, \( 987654321 \) squared is exactly \( 975461057789971041 \).
