How to count the Omer-The last day

 לז"נ הרב שמואל ב"ר מנחם דונאטה  זצ"ל

                                                                                                                                                                         יום השנה  ג' סיון

                                                                                                                                                               

The Chok Yackov* O. Ch. 489 quotes the Mahril that on the last day of Sefirah you

count היום תשעה וארבעים יום שהם שבעה שבועות בעומר ומחרתו ערב שבועות

The Pri Megadim asks ," where did the Mahril get this din and why would you need to add Umachroso Erev Shavuos to the counting of the last day of the Sefirah".

If you look inside the Mahril you will see that:

The Mahril says that on the last day you count Tisha V’arbaim Yom S’haim Shivah Shavuos  Baomer . PERIOD- STOP –NEW SENTENCE - Umachroso Erev Shavouos . 

This is not part of the counting, just  starting a new sentence and telling you about the following day.

The Chok Yaakov writes, "Tikun Leil Shavuos is only for Amei Ha'aratzim.  Talmidei Chachamim should learn instead ." 

Most Poskim argue on the Chok Yaakov and hold The Tikun contains deep Sodos and should be said by everyone.

The Chasam Sofer learned the Tikun with his Talmidim the

whole night  of Shavuos .