In addition to and largely independent of the division into suras, there are various ways of dividing the Qur’an into parts of approximately equal length for convenience in reading, recitation and memorization. The thirty ajza can be used to read through the entire Qur’an in a week or a month. Some of these parts are known by names and these names are the first few words by which the juz' starts. A juz' is sometimes further divided into two ahzab, and each hizb subdivided into four rub 'al-ahzab. A different structure is provided by the ruku'at, semantical units resembling paragraphs and comprising roughly ten ayat each. Some also divide the Qur’an into seven manazil to facilitate complete recitation in a week. Recitation “ ...and recite the Qur’an in slow, measured rhythmic tones. ” —Qur'