I n PuTTY's Application Keypad mode, the keys on the numeric keypad (including NumLock) can send special control sequences to the server. Depending on the application, this can cause the numeric keypad to behave differently.
If PuTTY appears not to recognize input from the numeric keypad, disabling Application Keypad mode will sometimes resolve the problem:
Click the PuTTY icon in the upper-left corner of the window. From the drop-down menu, click Change Settings. Click Terminal, and then click Features. Under "Enabling and disabling advanced terminal features", check Disable application keypad mode. Click Apply.