Messy data. A little practice. A cleaner sheet.

Challenge 01: Rescue the customer list

A customer export needs to be ready for import. Its 16 data rows include duplicates, a blank row, extra spaces, inconsistent capitalization, mixed date formats, and one missing email. All records are fictional.

Your cleanup checklist

• Remove the fully blank row and keep one record per customer_id. Repeated IDs contain the same customer data.
• Trim leading and trailing spaces and collapse repeated spaces inside names.
• Use title case for names and cities, and lowercase for emails.
• Convert dates to YYYY-MM-DD. Slash dates use US month/day/year; all signups are in August 2026.
• Convert orders to whole numbers. Keep zero orders and leave the missing email blank; do not invent a replacement.
• Keep the six original columns and sort by customer_id ascending.

In Excel, use Data → From Text/CSV. Keep customer_id and email as text. Save a working copy before you start.

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