Hello,

Consider the given 2 x 3 as [(2 x 3) *2 ] + 1 = 13.

Similarly, 3 * 4 is [(3 *4) * 2] +1 = [12*2] +1 = 24 + 1= 25.

Therefore, 4 * 5 is [(4*5) *2] +1= 41.

Hindi : " Jo numbers left mei diye gaye hai, uska multiplication karne ke baad, 2 se multiply karna hai.. fir wo result ko 1 add karna hai"

Hope this helps.

Thanks.