arithmetic

What is it that made the Harper government, which cannot guarantee it will survive until the weekend (although, yeah, it’s a pretty safe bet they will), decide to go for the 20-year, $30 billion defence plan instead of, say, the 10-year, $15-billion plan; the 100-year, $150-billion plan; the 6.5-year, $9.75 billion plan; or the indefinite, billion-and-a-half-per-year plan?