The word(s) "certain" appears 184 time(s) in 178 verse(s) in Quran in Mohsin Khan translation.

(171) And verily, it (this Qur'an) is an absolute truth with certainty.

(172) Whereon the heaven will be cleft asunder? His Promise is certainly to be accomplished.

(173) Verily, your Lord knows that you do stand (to pray at night) a little less than two thirds of the night, or half the night, or a third of the night, and also a party of those with you. And Allah measures the night and the day. He knows that you are unable to pray the whole night, so He has turned to you (in mercy). So, recite you of the Qur'an as much as may be easy for you. He knows that there will be some among you sick, others travelling through the land, seeking of Allah's Bounty, yet others fighting in Allah's Cause. So recite as much of the Qur'an as may be easy (for you), and perform As-Salat (Iqamat-as-Salat ) and give Zakat, and lend to Allah a goodly loan. And whatever good you send before you for yourselves (i.e. Nawafil non-obligatory acts of worship: prayers, charity, fasting, Hajj and 'Umrah), you will certainly find it with Allah, better and greater in reward. And seek Forgiveness of Allah. Verily, Allah is Oft-Forgiving, Most-Merciful .

(174) And We have set none but angels as guardians of the Fire. And We have fixed their number (19) only as a trial for the disbelievers, in order that the people of the Scripture (Jews and Christians) may arrive at a certainty [that this Qur'an is the truth as it agrees with their Books regarding the number (19) which is written in the Taurat (Torah) and the Injeel (Gospel)] and that the believers may increase in Faith (as this Qur'an is the truth), and that no doubt may be left for the people of the Scripture and the believers, and that those in whose hearts is a disease (of hypocrisy) and the disbelievers may say: "What Allah intends by this (curious) example ?" Thus Allah leads astray whom He wills and guides whom He wills. And none can know the hosts of your Lord but He. And this (Hell) is nothing else than a (warning) reminder to mankind.

(175) "Until there came to us (the death) that is certain."

(176) You shall certainly travel from stage to stage (in this life and in the Hereafter).

(177) certainly, your efforts and deeds are diverse (different in aims and purposes);

(178) And again, you shall see it with certainty of sight!