The same as it takes for any other skill - about 13 million experience points.
1,207 Experience.
The amount of experience for each level is the same for different skills. Details here: http://runescape.wikia.com/wiki/Experience
you will need a total off 7,842 exp in that skill.
1million or more
from lvl 1-70 attack you need 737,627xp You can quickly find out the amount of experience you still need, by using a fairly new feature: the feature to set an objective. Just set the objective to "attack 70", and you will see how much experience you still need. There are also several online RuneScape skill calculators; personally I use runescape.salmoneus.net. The advantage of a skill calculator is that it not only tells you how much experience you need, but also how much of this or that - for example, how many swordfish you have to cook to achieve a certain level of cooking. Alas, this particular calculator doesn't work with attack skills - and if any online calculator does, it will only be an approximation, since the amount of damage per strike varies.
It takes 13,034,431 experience to master strength in runescape.
You just try to get as much experience on the levels you can access. Once you beat the level, it will usually tell you how much xp you won, and using this you can see how much more xp you need.
The total exp is 13,034,431 experience for a 99 stat on RuneScape.
If you mean in RuneScape, it is not much less than from 1-99 - about 13 million. To get a more exact figure, you can do one of the following: 1) Search an online RuneScape guide, for example runescape.wikia.com, for "Experience". You'll find tables telling you how much experience is required for each level. 2) Pressumably you have a skill at level 76. Set the objective (by right-clicking on the skill) to level 99; if you then move your mouse over the skill, it will tell you how much experience points you still need. This is faster than the first method; also, it takes into account your exact experience points (for example, you may actually already be close to level 77).
Say you were on around 9m xp which is level 95, it would take to above 13m to get to level 99 so around 4m experience or so good luck on that.
250xp per log
It doesn't really matter much what you train; the amount of experience depends on the damage you deal. Just don't fight monsters that are too powerful (costs you too much food). It is convenient to go to monsters that are more than half your combat level, since monsters below that level are usually not aggressive (they don't attack you automatically). Also consider the combat triangle; for example, if you prefer to attack with magic, you have an advantage against creatures that attack with melee.