阅读程序，填写对应的输出结果

1. cout << 2.1 + 3.2 << endl;
   {{ input(1) }}
2. cout << 5.5 - 6.0 << endl;
   {{ input(2) }}
3. cout << 10.0 * 3.0 << endl;
   {{ input(3) }}
4. cout << 5.0 / 2.0 << endl;
   {{ input(4) }}
5. cout << 100.00 * 30000000.0 << endl;
   {{ select(5) }}

• 3000000000
• 3e+09
• 3e-09

6. cout << 4.0 / 100000000 << endl;
   {{ select(6) }}

• 4e-08
• 0.00000004
• 0.0000004