At least fifteen in my opinion
you cant. but you can get abs by doing bicycle crunches and regular crunches.
You won't get a six pack doing cardio. Look into weight lifting.
by doing 40 sit ups a day in a week in the morning and the after noon
Not very many, but doing all 100 of them in a row will give abs to your abs. I don't know but if you want to burn calories jogging is a better way to do it.
You can work out your abs every day, if you vary the exercises that you use. If you want to only do abs once or twice a week, you should do a number of different exercises on those days.
"Abs in a minute" or any other seemingly impossible exercise claims, are just that, impossible. For "abs in a minute" try doing crunches or sit-ups every day for a few minutes and see if that will improve your midsection in a few days, weeks or months.
No.
I would assume the same number of abs any human has.
YES!!! i have been doing sit ups for about 4 weeks now... About 250 a day and my stomach is clearly getting flatter and i can see my abs more clearly.
about 500-600
It all depends on how many you are doing, also keep in mind that sit-ups aren't as effective as crunches, crunches will get you abs much quicker... also, you must be exercising fairly frequently (read everyday), not just doing sit-ups, if you want abs.
Every other day.