Re: “Trudeau’s public support has grown exponentially: reader,” (The Hill Times, March 14, p. 8). Really? When mentioning mathematical rates of increases, there are three types: for example, 2+5=7, 2x5=10, 25=32. Only the last example is “exponential” and is the fastest growing. However, one needs to see some previous data to identify an exponential rate. That was missing from the original letter. Darrel Kennedy Ottawa, Ont.