The word(s) "why" appears 77 time(s) in 72 verse(s) in Quran in Abdullah Yusuf Ali translation.

(61) And ye certainly know already the first form of creation: why then do ye not celebrate His praises?

(62) Were it Our Will, We could make it salt (and unpalatable): then why do ye not give thanks?

(63) Then why do ye not (intervene) when (the soul of the dying man) reaches the throat,-

(64) Then why do ye not,- If you are exempt from (future) account,-

(65) What cause have ye why ye should not believe in Allah?- and the Messenger invites you to believe in your Lord, and has indeed taken your Covenant, if ye are men of Faith.

(66) And what cause have ye why ye should not spend in the cause of Allah?- For to Allah belongs the heritage of the heavens and the earth. Not equal among you are those who spent (freely) and fought, before the Victory, (with those who did so later). Those are higher in rank than those who spent (freely) and fought afterwards. But to all has Allah promised a goodly (reward). And Allah is well acquainted with all that ye do.

(67) Turnest thou not thy sight towards those who were forbidden secret counsels yet revert to that which they were forbidden (to do)? And they hold secret counsels among themselves for iniquity and hostility, and disobedience to the Messenger. And when they come to thee, they salute thee, not as Allah salutes thee, (but in crooked ways): And they say to themselves, "why does not Allah punish us for our words?" Enough for them is Hell: In it will they burn, and evil is that destination!

(68) O ye who believe! why say ye that which ye do not?

(69) And remember, Moses said to his people: "O my people! why do ye vex and insult me, though ye know that I am the messenger of Allah (sent) to you?" Then when they went wrong, Allah let their hearts go wrong. For Allah guides not those who are rebellious transgressors.

(70) and spend something (in charity) out of the substance which We have bestowed on you, before Death should come to any of you and he should say, "O my Lord! why didst Thou not give me respite for a little while? I should then have given (largely) in charity, and I should have been one of the doers of good".