5453246435 X 9999999999 in 5 Sec

That seem tough, but it is not...

notice that both have 10 digit ..... this process is valid only when no. of. digit are equal and the second digit has only nine repeated...........

FOR MORE TRICKS CLICK ON

https://www.instructables.com/id/Make-Maths-EZEE/

Lets start with a simple one 5245 * 9999

on the right sides write the number by following the "All from 9 and the last from 10" rule or subtract the (first number) from (second number + 1)..........

10000 - 5245 = 4755

"All from 9 and the last from 10" is a easier method for finding it..........

now subtract 1 from the first number that is 5245 - 1 = 5244

placing them one after the other

5244 4755

5245 * 9999 = 52444755

try out 54364576658736326353*99999999999999999999 on your own

5245 * 9999

= 5245 * (10000 - 1)

= 52450000 - 5245

= 52430000 + 10000 - 5245

= 52430000 + (10000 - 5245)

= 52430000 + 4755

= 52444755

PROVED.........