[Math] How to calculate how many digits in a number from index notation

Question

How can you calculate how many digits are in a number from its index notation?

I need to calculate how many digits are in the number $2^{30} * 5^{25}$

Answer 1

$2^{30}\times5^{25} = 10^{25}\times2^{5} = 32 \times 10^{25}$

Edit

So, there are two digits for 32 and 25 zeros after it. 27 in total.