qmk_firmware_custom/keyboards/felix/keymaps/default/keymap.c

#include QMK_KEYBOARD_H

const uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {
    LAYOUT_ortho_5x4(
        KC_NLCK, KC_PSLS, KC_PAST, KC_PMNS,
        KC_P7,   KC_P8,   KC_P9,   KC_PPLS,
        KC_P4,   KC_P5,   KC_P6,   KC_HOME,
        KC_P1,   KC_P2,   KC_P3,   KC_END,
        KC_P0,   KC_PEQL, KC_PDOT, KC_PENT
    )
};