The realization that a day can signify a year is of crucial importance in the study of the bible numbers. (And concerning the bible codes: Each letter of the bible can symbolize one year too!)

Steve Gregg in his parallel commentary on the four main Protestant views of Revelation lists a number of outstanding theologians who have held the "historicist" view. (The "historicist" regards the Book of Revelation as a survey of the whole of Church history. Personally, I find that all four views compliment one another.)

Concerning the historicist view, Gregg says: "A unique characteristic of this line of interpretation is its advocacy of what is called the "year-for-a-day principle."’" He lists the following among the adherents of the historicist view:

"John Wycliffe, John Knox, William Tyndale, Martin Luther, John Calvin, Ulrich Zwingli, Phillip Melanchthon, Sir Isaac Newton, Jan Huss, John Foxe, John Wesley, Jonathan Edwards, George Whitefield, Charles Finney, C. H. Spurgeon, Matthew Henry, Adam Clarke, Albert Barnes, E. B. Elliot, H. Grattan Guinness, and Bishop Thomas Newton." (S. Gregg, "Revelation: Four Views," Nashville: Thomas Nelson Pub, 1997, p. 34.)

• Bible Numbers: A day can equal a year:

The following are some examples of a day representing a year:

"And your children shall wander in the wilderness forty years, and bear your whoredoms, until your carcasses be wasted in the wilderness. After the number of the days in which you searched the land, even forty days, each day for a year, shall ye bear your iniquities, even forty years..." (Numbers 14:33,34a)

"Lie thou also upon thy left side, and lay the iniquity of the house of Israel upon it: according to the number of the days that thou shalt lie upon it thou shalt bear their iniquity. For I have laid upon thee the years of their iniquity, according to the number of the days, three hundred and ninety days: so shalt thou bear the iniquity of the house of Israel. And when thou hast accomplished them, lie again on thy right side, and thou shalt bear the iniquity of the house of Judah forty days: I have appointed thee each day for a year" (Ezekiel 4:4-6).

"Seventy weeks are determined upon thy people and upon thy holy city ... from the going forth of the commandment to restore and to build Jerusalem unto the Messiah the Prince shall be seven weeks, and threescore and two weeks ... And after threescore and two weeks shall Messiah be cut off, but not for himself: and the people of the prince that shall come shall destroy the city and the sanctuary; and the end thereof shall be with a flood, and unto the end of the war desolations are determined. And he shall confirm the covenant with many for one week: and in the midst of the week he shall cause the sacrifice and the oblation to cease..." (Daniel 9:24-27)

The "week" referred to here represents (primarily) a symbolic seven-year period. Thus once again, one day is made to signify one year. Here is why Daniel's "week" denotes seven years:

a) This vision (of ch. 9) came to Daniel upon his understanding that the 70 years of Israelite exile (as prophesied by Jeremiah) had just elapsed:

"In the first year of his reign I Daniel understood by books the number of the years, whereof the word of the LORD came to Jeremiah the prophet, that he would accomplish seventy years in the desolations of Jerusalem" (Daniel 9:2).

It is reasonable to deduce that since the occasion for Daniel's vision was his understanding of the 70 years of Jeremiah, and that since the vision to Daniel concerned a like number of 70 weeks, therefore 70 weeks can equal 70 (x 7) years. Nevertheless, Daniel's "week" as a literal 7-day-period is also a valid interpretation. Both days and years weave together.

b) Seventy literal weeks would not be enough time to accomplish all the things mentioned as having to transpire within the scope of Daniel's "seventy-weeks" vision. For this reason, most scholars I have read view the seventy weeks of Daniel as symbolic years.

c) The Hebrew term for "weeks" is actually the plural of the word for "seven," without specifying whether it is days, months, or years; (see Walvoord "Daniel: The Key to Prophetic Revelation", p. 219).

d) Daniel's "seven-weeks" (49 days) can be understood symbolically as 49 years because of it's similarity with the seven weeks (49 days) till Pentecost; and the seven weeks of Pentecost follows the patters of the seven-times-seven years (49 years) of the Jubilee, (Deut. 16:9, Lev. 25:8). 

e) The "dividing" of the last "week" of the 70 "weeks" is further explained in Daniel 12:9, where the 1290 days is mentioned. One-half ("dividing") of "one week" (i.e., of 7 years) amounts to this 1290  days; (i.e., 3.5 x 360 = 1260, + leap month = 1290 days). Hence, one "week" must symbolize years in order for half-a-week to total 1290 days (instead of a literal 3½ days). 

A fuller treatment of the 1290 shall be explained elsewhere, but for now please note the following:

i) The 390 + 40 = 430 days/years of Ezekiel (mentioned earlier) are exactly one-third of 1290, (cf., Ezk. 4:4-8, 5:2. I.e., 430 d/y x 3 = 1290 d/y). 

ii) The time from when Ezekiel was told to lay on his side 430 d/y's symbolizing the siege of Jerusalem (593 BC), until the end of the literal siege of Jerusalem (586 BC), are 7 full years, or 3½ + 3½ years. 

iii) The total siege-length of Ezekiel's symbolic siege of 390 (+ 40) days, plus the 945 days of the literal siege, amounts to 1335 days---the same figure found coupled with the 1290 days in Daniel 12:9.  

iv) The fact that there are 1290 years from the entry into Egypt (1876 BC, which lasted 430 years until the exodus, 1446 BC), until the exile back again into Egypt (and Babylon) at the fall of Jerusalem (586 BC), is proof positive that 1290 days are intended to be years as well.

v.) See www.360calendar.com for more.

• Bible Numbers: A day can equal a 1000 years:

"But, beloved, be not ignorant of this one thing, that one day is with the Lord as a thousand years, and a thousand years as one day..." (2Peter 3:8,10). 
{Compare this in context also with Revelation 20:2-7.}

Peter seems to be quoting Moses in the book of Psalms. 

"Lord, you have been our dwelling place throughout all generations...You turn men back to dust, saying, "Return to dust, O sons of men." For a thousand years in your sight are like a day that has just gone by, or like a watch in the night." (Psalm 90:1,3,4)