How to insert multiple empty columns at the same time in Excel 2007?

To insert multiple columns at the same time, consider the figure to the right. The following data is missing:
Column C, row number 1 (cell C1) : March
Column D, row number 1 (cell D1) : April

Here, we have to insert two columns that are next to each other or two adjacent columns with the data March and April and move the other columns to the right. Notice that we have to insert two columns between column number B and C. To insert two columns, perform the following:
1. Click the column header C.
2. Press and hold the SHIFT key. Click the column header D. Now two columns will be highlighted.
3. Right-click on any highlighted column in the column header and click Insert.

We will consider another case where we will insert non-adjacent columns. Consider the figure to the right. The following data is missing.
Column C, row number 1 (cell C1) : March
Column F, row number 1 (cell F1) : June

Here, we have to insert 2 columns but the insertion points are between column number B and C, and column number D and E. To insert two columns, perform the following:
1. Click the column header C.
2. Press and hold the CTRL key. Click the column header E. Two non-adjacent columns will be highlighted now.
3. Right-click on any highlighted column and click Insert.

Here's a brief summary:
1. Click to highlight the first column where you need to insert a column.
2. To insert adjacent columns, press the SHIFT key and click the last column. To insert non-adjacent columns, press the CTRL key and click to select other columns.
3. Right-click on any highlighted column and click Insert.

You may try inserting adjacent and non-adjacent columns at the same time.