Division is breaking a number up into an equal number of parts. If you take 40 things and put them into four equal sized groups, there will be 10 things in each group. The answer is 10.
As you all know how complex it is to multiply multiple digits number in targeted time frame. But if you practice the tricks and formulas it becomes a play to solve maths problems. The Maths puzzle book by Sakuntala Devi is the awesome work of these techniques and formulas. It will surely sharpen you mind.