Google PRINCIPLES OF MOBILE SITE DESIGN: DELIGHT USERS AND DRIVE CONVERSIONS - Manual (Page 26)

14. STREAMLINE
INFORMATION ENTRY
Participants were pleased when sites automatically
presented number pads for entering values like zip
codes or birth dates. They also appreciated forms that
automatically advanced through fields as they entered
information. Conversely, they got frustrated when they
had to repeatedly tap small form fields and switch their
phone keyboard to numeric mode.
Example from Delta Mobile Site.
Key Takeaway
Offer users a number pad for fields
requiring number entry, and automatically
advance them through form fields as they
input information.
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