This is one of the common question asked by people who are aware about vedic math, but do not what exactly it is. For those who have never heard this, they prefer to ignore this as this is not "recommended" by the reference book given to them. However, Vedic Mathematics or Vedic Math is important to any person who if given GMAT as this essentially helps you to do quick calculation and save a lot of time. And I suppose, time does become one of the major factor while appearing for GMAT.

This is a quote I found of a student appearing for GMAT and who has tried Vedic Math.
"I have studied Vedic Maths and don't think that it alone will help you get over your quant problems. For quant, you will have to study from the regular stuff - og, kaplan, manhattan, princeton or whatever u prefer ..

Vedic maths is extremely useful for getting super good at basic maths operations and calculations.. it does improve your speed a lot. However, it needs to be used together with the standard material to help anyone in GMAT"

I would like to repeat - Vedic Mathematics is useful for getting SUPER GOOD at basic math operation and calculation. I agree but at the same time I have to add that this person may have only gone through basic's of vedic mathemetics. There are more advanced material available [not covered in the 10 day course]. At the end of the program which I have designed, I will show you certain website from which you can sure benefit.

Other Web Sources:
"Vedic math is an ancient process of speedy mental math.. originating in India… the famous mathematican Ramanujan was a professed vedic mathematician… he solved the riehman problem using his vedic mathematical techniques.. his formula is what today's atm money system is based on as well…"

"Vedic mathematics sure will help with the pace of solving the problems. but, i suggest use the shortcut method that are recommended for elementary calculation like multiplication, division, sq. roots, squaring, cubes ,etc."

I would suggest everyone to take this 10 day free course and then you decide for yourself whether you need this. 10 days is not going to hurt you much.