You will find in the attached docx file what to do. You will find the formula to calculate the laterality quotient in:

Oldfield, R.C. (1971) The assessment and analysis of handedness: the Edinburgh inventory. Neuropsychologia, 9, 97–113.

Alternatively you may use:

1)Annett, M., 1970. A classification of hand preference by association analysis. Br. J. Psychol. 61, 303–321.

2) Porac, C., Coren, S., 1981. Lateral Preferences and Human Behaviour. Springer-Verlag, New York

I hope helping you

Theodoros

thanks Theodoros.

and one more question is what is the cut off score for right and left handed?

Thanks Simon for your answer

Four years ago, I developed a user-friendly online tool for handedness assessment based on the 10-item Edinburgh Handedness Inventory. http://zhanglab.wikidot.com/handedness

Some researchers have raised methodological issues about the self-reported assessment of handedness and argued for a modification of using 7 items of hand preference by dropping drawing, broom, and opening box-lid from the 10 items . See the two articles below for discussion.

Article Modification of the Edinburgh Handedness Inventory: A replic...

Article Differences between left- and right-handers in approach/avoi...