what is 999999999999999999 times 9999?

2 answers

What do you think the answer is? We'll be glad to check your answer if you post it here.
999999999999999999 =

10^18 - 1

9999 = 10^4 - 1

999999999999999999 * 9999 =

(10^18 - 1)* (10^4 - 1) =

10^22 - 10^18 - 10^4 + 1