Suppose that the production function is given by Y$=$AK$^0\mathrm{.}4$N$^0\mathrm{.}6.$ What is the change in output if both capital and labor rise by $31\%$ and total factor productivity falls by $31\%?$ The answer is $0.$Since the production function is constant Returns to Scale, when both K and N rise by $31\%,$ so does output. But since A is falling by $31\%$ also, this by itself lowers output by $31\%.$ Hence, the overall effect on output is $0.$ But I don't understand the answer. My calculators says: Assume A $=1,$ K$=1,$ and N$=1$: $(1$ : $0\mathrm{.}69)(1.1\mathrm{.}31)0\mathrm{.}4(1$ : $1\mathrm{.}31)0\mathrm{.}6=0\mathrm{.}903910\mathrm{.}4.10\mathrm{.}61.$ Assume A $=2,$ K $=3,$ and N $=5$: $(20\mathrm{.}69)(3.1\mathrm{.}31)0\mathrm{.}4.(5.1\mathrm{.}31)0\mathrm{.}62-(3)0\mathrm{.}4.(5)0\mathrm{.}6=0\mathrm{.}9039$ Why the answer is $0,$ not $0\mathrm{.}9039?$ Please give detailed explanation. Thank you.