2021 JMPSC Problems/Problem 2

Problem

Brady has an unlimited supply of quarters (0.10), nickels (0.01). What is the least number (quantity, not type) of coins Brady can use to pay off $$ (Error compiling LaTeX. Unknown error_msg)2.78$?

== Solution ==

To minimize the number of coins, we need to maximize the amount of high-valued coins we use. 11 quarters are worth$ (Error compiling LaTeX. Unknown error_msg), which is the most quarters we can use to get a value less than or equal to $$ (Error compiling LaTeX. Unknown error_msg)2.78, so the answer is .