Question: how to change mobile number in aadhar card online (aadhar card mobile number update )?
Answer: Step 1: Go to the official portal of Aadhaar here https://ask.uidai.gov.in/
Step 2: Login by entering your mobile number and captcha. ... 
Step 3: Next, Enter the received OTP on the right-hand side box and click 'submit OTP and process.