Number of strings =

= 21 x 21 x 21 x 21 x 21 x 5 = 20 420 505
Answer: 20 420 505
If all were dimes, the value would be $3.30. Brendan has $2.85 more than that. Each quarter that replaces a dime increases the value by $0.15, so Brendan must have $2.85/$0.15 = 19 quarters.
Brendan has 14 dimes and 19 quarters.
No, it is an imaginary number.
Can't take the square root of a negative number without creating a method termed an imaginary number, which is the square root of -1 which they have used " i " to signify.
Then square root of -11.2 would be written Sqrt(11.2)i. The Sqrt(11.2) = 3.3466
so the answer is 3.3466i