When candles are in short supply, or you don’t really want to have your age on your cake, here’s a neat dodge.
http://www.mathsisfun.com/binary-decimal-hexadecimal-converter.html
First, convert the birthday of the person to binary from decimal, using the handy converter above.
Second, light ONLY the candles showing as one. So, for my last birthday (53) you put up 6 candles and light the first, second, fourth and sixth.
I’m 35 in hex, by the way.