Power up to 1000
Find $x+y$, where $2^x\times5^y=1000$
Age
14 to 16
Challenge level
Problem
Student Solutions
Answer: $6$
Index laws
$
So $x=3$ and $y=3$, so $x+y=6$.
Calculating directly
$
So $x=3$ and $y=3$, so $x+y=6$.