Another way to think about it: for every 100 units in 10, you take 61. That adds up to 6.1.
On a 61% off sale, an item originally priced at $10 would be discounted by $6.1, bringing the price to $3.9.
Whether you are calculating a discount, a tax, a tip, or a commission, the math is always the same: multiply 10 by 0.61.