I need to compute 987654321².

Let me break this down using the formula (a - b)² = a² - 2ab + b².

I'll write 987654321 = 1000000000 - 12345679

So:
987654321² = (1000000000 - 12345679)²
= 1000000000² - 2(1000000000)(12345679) + 12345679²

Let me calculate each term:

**First term:**
1000000000² = 1000000000000000000

**Second term:**
2(1000000000)(12345679) = 24691358000000000

**Third term:**
12345679² = ?

Let me compute 12345679²:
12345679 = 12345679
12345679² = (12345679)²

Using (a - b)² where 12345679 = 12500000 - 154321:
Actually, let me compute directly:
12345679² = 152415790139971041

**Combining all terms:**
987654321² = 1000000000000000000 - 24691358000000000 + 152415790139971041

= 975308642000000000 + 152415790139971041

= **975461057139971041**

Therefore, 987654321² = **975461057139971041**
