how do I block number 1 number on samsung galaxt core smart phone

Blocking Calls From a Specific Number:

1. Tap the "Phone" icon located on the home screen
2. Press the "Menu" key
3. Tap "Call Settings" > "Call rejection"
4. Tap "Auto reject mode" > "Auto reject numbers"
5. Press the "Back" button and tap "Auto Reject List"
6. Tap the "+" icon next to "Create"
7. Type in the phone number that you want to add to the list of "Blocked Calls"
8. Optionally, select to "Match criteria", and choose "Exactly the same as" (to block that exact number), "Starts with" (to block phone calls from a certain area etc.)
9. Tap "Save"

Unblocking a Number:

1. From the home screen, tap the "Phone" icon
2. Press the "Menu" button
3. Tap "Call Settings" > "Call rejection"
4. Tap "Auto reject list" and tap the "trash can" icon
5. Mark the check box associated with the number that you want to unblock
6. Tap "Delete", and press "Delete" a second time to confirm

Blocking Calls Using Applications:

Assuming that the call blocking features offered by the Galaxy Light are not enough to meet your needs, then you can try various third party applications that offer a wider range of blocking features, such as "Call Blocker", "Call Blacklist" and / or "Call Control" (or other similar apps). Most of these applications come with blacklists, they offer to block text messages, offer call logs, password protection and more.