Calculate by pattern matching

I need help to calculate the average based on SKU patterns.

For example, if the SKU begins with "CZD", then take the average SKU that meets that pattern.

[TABLE="width: 327"]

[tr]

[TD="class: xl24, width: 210, bgcolor: transparent"]SKU[/TD]
[TD="class: xl24, width: 117, bgcolor: transparent"]Items Sold[/TD]

[/tr]

[tr]

[TD="class: xl23, bgcolor: transparent"]CZD80[/TD]
[TD="class: xl23, bgcolor: transparent, align: right"]45[/TD]

[/tr]

[tr]

[TD="class: xl22, bgcolor: transparent"]AAK99[/TD]
[TD="class: xl22, bgcolor: transparent, align: right"]46[/TD]

[/tr]

[tr]

[TD="class: xl22, bgcolor: transparent"]CZD50[/TD]
[TD="class: xl22, bgcolor: transparent, align: right"]14[/TD]

[/tr]

[tr]

[TD="class: xl22, bgcolor: transparent"]AAK45[/TD]
[TD="class: xl22, bgcolor: transparent, align: right"][/TD]

[/tr]

[tr]

[TD="class: xl22, bgcolor: transparent"]HHU22[/TD]
[TD="class: xl22, bgcolor: transparent, align: right"]76[/TD]

[/tr]

[tr]

[TD="class: xl22, bgcolor: transparent"]PPH34[/TD]
[TD="class: xl22, bgcolor: transparent, align: right"]100[/TD]

[/tr]

[/TABLE]