Question

What does 7263×27 equal

Answer 1

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