Hashem yimloch l’olam va’ed Hashem shall reign for all eternity.
There is a short but very powerful pasuk we say each morning in Shacharis. Rav Efrem Goldberg, Senior Rabbi of the Boca Raton Synagogue, quoted a Kaf HaChayim, which said that if one says this pasuk 45 times, it is as if he said Amen 90 times. Some strive to respond Amen to 90 brachos daily. The Kaf HaChayim wrote that he personally recites this pasuk 45 times each morning in order to make sure he has fulfilled his 90-Amen goal. At the current time, since we are not able to go to shul, which is where the overwhelming majority of the 90 Amens would normally come from, reciting this pasuk 45 times would seem to provide a great opportunity for those who are careful to get their 90 Amens.