This process is called crossing over. It happens when the homologous chromosomes pair up.
Since it is easily calculated using a calculator, I assume you need this done in the head.
Yes, you can do that.
It takes a few words to explain this, but if you understand how this is done, it goes fast.
27=3*9
so 7263*27 = (7263 * 3) * 9
so first multiply 7263 by 3.
72*3=216, 63*3=189
so 3*7263=21789
So far so good.
Now you can multiply anything by nine by subtracting from the right neighbour, starting from the right.
For example, 27*9. the right neighbour of 7 is 0, borrow 1, so 10-7=3
the right neighbour of 2 is 7, but we borrowed 1, so 6. 6-2=4
At the beginning of the number 27, we add a zero which we subtract from the right neighbour 2 to get 2.
So 27*9=243.
Now for 21789, we have successively
(10)-9=1
8-8=0 (9 was borrowed to become 8)
8-7=1
7-1=6
(11)-2=9
and finally
1 -0 = 1 (2 was borrowed to become 1)
So the final answer is 196101
